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TEMPORAL FACTORS ASSOCIATED WITH =
MEASUREMENTS OF ORAL STEREOGNOSIS

Thesis for the Degree of Ph. D.
MICHiGAN STATE umvmsrrv
KENNETH GORDON SMITH
1973

 

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Michigan State
University

 
   

This is to certify that the
thesis entitled

Temporal Factors Associated with
Measurements of Oral Stereognosis

presented by

Kenneth Gordon Smith

has been accepted towards fulfillment
of the requirements for

Ph. D. degree in Speech Pathology

[Wt/é 4/

Major profe or

Date August 24, 1973 is

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TEMPORAL FACTORS ASSOCIATED WITH
MEASUREMENTS OF ORAL STEREOGNOSIS

By
Kenneth Gordon Smith

AN ABSTRACT OF.A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for;the degree of

DOCTOR OF PHILOSOPHY
Department of Audiology and Speech Sciences
1973

ABSTRACT

TEMPORAL FACTORS ASSOCIATED WITH
MEASUREMENTS OF ORAL STEREOGNOSIS

By
Kenneth Gordon Smith

In the recent study of oral sensation and perception the
question of temporal factors associated with measurements of
oral stereognosis has received scant attention. This study
compared the effects of varying three temporal factors asso-
ciated with administrating a test of oral stereognosis.

The first factor was intra-oral duration of stimulation
by a single form (3, 5. and 7 seconds). The second factor
was the interval between the two items within each pair of
forms (3, 5, and 7 seconds). The third factor was the inter-
val between presentation of pairs of forms (5. 7. and 9
seconds). These three factors were referred to in abbre-
viated forms intra-oral duration. within-pairs interval, and
between-pairs interval respectively. The stimuli employed in
this investigation were ten geometric plastic forms known as
the Ringel Forms.

Before the actual experiment, cassette tapes were pre-
pared with tones marking time periods appropriate for
presenting the stimuli. These tones provided auditory cues
to the examiner and the subjects indicating the various com-
binations of the three temporal factors. 45 young adults
with normal articulation and hearing received 27 treatments..
‘including all possible combinations of the three intra-oral
durations, the three within-pairs intervals, and the three

between-pairs intervals. Each treatment consisted of 55

Kenneth Gordon Smith
pairs of Ringel Forms which was the total number of pairings
possible when each form was paired with itself and with every
other form. The subjects were required to indicate verbally
whether the two items in each pair of forms were the same or
different in a simple discrimination task, as the forms were
placed on the tip of the tongue for passive perception.

Results indicated significant differences in number of
errors (p<0.05) for the factors of within-pairs interval and
between-pairs interval. Although there was not a statisti-
cally significant main effect for the factor of intra-oral
duration, there was more difference in number of errors be-
tween the three-second and five-second durations than between
the five-second and seven-second durations. The results in-
dicated that as the within-pairs interval increased the
error score increased, but that as the between-pairs interval
increased the error score decreased. These results sup-
port the suggestion that short-term memory is a significant
consideration in performance on this task.

It was concluded that in the clinical application of a
test of oral stereognosis, employing the stimuli and tech-
niques described in this study, the intra-oral duration
should be five seconds, the within-pairs interval should be
three seconds, and the between-pairs interval should be nine
seconds. It was also suggested that some of the pairs of
forms were redundant and could be eliminated in the clinical

situation.

TEMPORAL FACTORS ASSOCIATED WITH
MEASUREMENTS OF ORAL STEREOGNOSIS

By
' Kenneth Gordon Smith

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Audiology and Speech Sciences

1973

\5 Accepted by the faculty of the Department of Audiology

and Speech Sciences, College of Communication Arts. Michigan
State University, in partial fulfillment of the requirements
for the Doctor of PhilosOphy degree.

,1

/'/-"_ if //7
/ ,’ z ‘
Thesis Committee: L 42(1 //<::igéc4zf:__~nirector

an el . Beasley, Ph.D.

é? Kg§ *EJ ' Co-Direotor
Yo Kapur, e e

 

 

ACKNOWLEDGMENTS

In the course of investigation as reported in this
thesis, I have expressed by heartfelt thanks to the members
of my committee. Now, I take this opportunity to formally
express my gratitude to Dr. Barch, Dr. Deal. Dr. Oyer, and
the Co-Director of my thesis. Dr. Kapur. The words of
encouragement, and the detailed constructive criticisms
these professors have offered have been most welcome support
during the months of research and writing.

I wish to pay special tribute to my Director. Dr.Beasley
for his sustained moral support, clear discernment of the
issues important to my research. as well as detailed sugges-
tions at every stage of the research.

Lastly, and most importantly, I thank my dear wife,
Elfriede, for her patience, love and prayerful support
through many trying months.

Kenneth G. Smith

ii

TABLE OF CONTENTS

CHAPTER Page
LIST or TABLES..................................... v
LIST or FIGURES.................................... vi
I. INTRODUCTION..................................

Definitions................................
KinestheSi-SOOOIOOOOOOOOOOOOOOOOOOOOOOIOO
Proprioception..........................
Stereognosis............................
Oral Stereognosis.......................

Theoretical Considerations on Oral
Stereognosis............................

Relative Sensitivity of Oral Structures.... ll

Intra-Oral Discrimination versus Visual
matChj-ng TaSkSOOOOOOOOOOOOOOOOO0.00.0... 12
Statement of the Problem................ 18

must: H

0\

II. EDERINENTAL PROCEDURES...IOOOOOOCO0.0.0.0.... 20

subjects 0 C C C O O O O I O O O O O 0 O O O O O O O O C O O O O O O I O O . C 20
Experimental Conditions.................... 20
Procedures 0 O O C O O O I I O O O I O Q 0 O O O O O O O I O O O O O O O O O 21

III. RESULTSOOIOOOOOQOeeeeeeeoeeeOOOOOOIoeeeeeeeeeo 25

Effect of Different Levels of Within-
Pairs Interval.......................... 25
Effect of Different Levels of Between-
Pairs Interval.......................... 28
Effect of Different Levels of Intra-Oral
Duration OOOOOOOOOOOOOOOCIOOOOO00.00.... 28
Difficulty in Discriminating Pairs of
Fomsooeoeooeeeeeeoeeoeeeeeeeeeeeeeeeeeo 3].

Iv. DISCUSSIONOOOOOOO000000eeeeoeooeeeeoeeeeeeeoOO 32
Intm-Oml Dumtionleeeeeeeeoeeeeeeeeeeeeee 32

Within-Pairs Interval...................... 34
Differential Difficulty of Pairs of Forms.. 36

iii

TABLE OF CONTENTS - Continued
CHAPTER Page
Procedural Considerations.................. 38
Considerations for Clinical Application.... 39
Considerations and Suggestions for
Future Research......................... 41
BIBLIOGRAPHYOCOOCO...O...COO...OOOIOOOOOOOOOOOOOOOO 2+5
APPENDICES
A. ANALYSIS OF VARIANCE TABLE................. 51

B. DATA MATRIX SHOWING THE DESIGN
OF TI'IE STUDY... oooooo eooeeeaoooo ...... ea 52

C. INSTRUCTIONS To SUBJETS.COIOOOOOIOOOIIOOOO 53

D. ACTUAL SHAPES AND SIZES OF THE RINGEL
SET OF FORMSCCCOOOOOCIOOI.COCOIOOOOCC... 55

E. ARRANGEMENT OF EQUIPMENT USED IN TESTING
SUBJECTSIQOOOIOII.OOOCCIOCOOOIOOQOOOOOOC 56

F. THE FIFTY-FIVE PAIRS OF FORMS USED IN
Tm EDERIMNTCOOO0.00.000.00.000.0.00.. 57

iv

TABLE

LIST OF TABLES

Page
Mean error scores for each level of each
factor under study (Intra-Oral Duration,
Within-Pairs Interval, Between-Pairs
Interval)000000000000.00000000000000000000000. 26
Mean number of errors as a function of
Intm'oml Durationooeeeeeeeeeoeeeeoeeeeeeeeeo 30

Percentages of errors made on pairs of forms
from the Ringel setCOOOOOOOIOOOOOOOOOO0.00.... 30

LIST OF FIGURES
FIGURE . Page

1. main effect of the within-pairs interval...... 27
2. Main effect of the between-pairs interval..... 29

vi

CHAPTER I

INTRODUCTION

The case load of a speech pathologist typically reveals
a predominance of individuals with articulatory deficits
(Johnson, Darley and Spriestersbach. 1963). Many of these
individuals are categorized as having ”functional articula-
tion" problems. The speech pathologist has either accepted
this label from other professional personnel or has himself
so diagnosed the deficit. The diagnoSis is typically based
on an evaluation in which.an articulation test and an oral
examination are important aspects. The oral examination con-
sists of a visual inspection of the oral cavity and observa-
tion of the response elicited when the client is told to
move the articulators in certain prescribed ways.

Recently, some investigators (Jenkins and Lohr. 1964;
McDonald, 196A; Aungst, 1965; Ringel et al.. 1968: Fucci and
Robertson, 1971; Fucci, 1972; and Ruscello and Lass, 1973)
have questioned the use of terms such as ”functional.”
"non-organic,” and "developmental“ as applied to articulatory-
impaired individuals. They have contended that these terms
may be misleading if applied to articulatory deficits which
are not recognized as organically based because of the lack

1

2
of precision of the presently available measuring devices.

Whereas the auditory channel has been employed predom-
inantly in diagnosis and therapy of speech disorders. the
evidence suggesting that certain cases of ”functional” speech
disorders are related to reduced feeling in the mouth may
have important implications for speech pathology (La Pointe
and Williams, 1972). If, in diagnosis of articulatory defec-
tive speech, apprOpriate tests can determine whether the
cause is primarily motor or sensory. then planning therapy
would be greatly enhanced.

Recent considerations in the theory of speech produc-
tion, to be discussed later. have influenced researchers in
speech pathology to look upon speech as a behavior which can
be modified more effectively by training procedures that
involve speech rather than nonspeech acts (Shelton et al.,
1970b). If, as Fucci and Robertson (1971) suggest. the term
”functional” is not always appropriate for non-organic
articulation cases. then perhaps speech pathologists should
consider the employment of a therapeutic approach which would
allow for correction of, or compensation for. sensory defi-.s
cits. Fucci and Robertson suggest using an oral-tactile
orientation which may be more suitable in some individual
cases as a rehabilitative method.

Building on the concepts of Fairbanks' servosystem model
of speech production (Fairbanks, l95fl), ”servotherapy' has
been suggested as an alternative treatment for use by speech

therapists (mysak, 1959). In such an approach. the therapist

3

tries to superimpose his speech system upon the client's.

The aim is to begin with this open cycle control (using stim-
ulation and guidance techniques), which hapefully will become
a closed cycle control as the client internalizes the new
formations and begins monitoring his own performance (mysak.
1959)-

Reoognition of the limitations of the procedures now in
use in speech pathology has prompted considerable effort to
study and develop methods of testing oral sensation and per-
ception (Bosma, 1967 and 1970). Studies in the area of oral
sensation and perception may be divided into those studies
concerned with oral sensory thresholds (McCall. 1969: Ringel.
1970. McCall and Cunningham, 1971. Fucci. 1971 and 1972.
Fucci et al., 1972;.Ha11 et al., 1972. Lass et al.. 1972a.
Telage et al., 1972; and Williams and La Pointe, 1972), and
oral sensory discrimination (Aungst, 1965; Arndt et al.,
1970a; Arndt et al., 1970b; Fucci and Robertson, 1971; Bain.
1973: La Pointe and Williams, 1973; and Torrans and Beasley.
1973).

The review of literature pertinent to a Study of oral
sensation and perception has been divided into four sections:
(1) Definitions. (2) Theoretical considerations on oral ster-
eognosis. (3) Relative sensitivity of oral structures.

(4) Intra-oral discrimination versus visual matching tasks.

This chapter closes with a Statement of the problem.

4
Definitions

Kinesthesis

This sense conveys knowledge of position as well as
movement and is probably man's most important sensitivity,
enabling a person to maintain an erect posture as well as
walk, talk, and engage in other skilled activities (Jenkins,
1951). Kinesthetic sense is mediated by the nerve endings
embedded in the tissues of the muscles, tendons and joints.
These nerve endings are stimulated by the pressure and strain
resulting from movement (Gray and Wise, 1959). =The primary
stimulation of the tendon endings occurs when the muscle con-
tracts. The muscle endings are activated as a muscle relaxes
and lengthens when its antagonist contracts. So the muscle
and tendon endings complement each other in recording muscu-
lar changes. Sensitivity at the joints may be mediated by
Pacinian corpuscles which are found abundantly in the tissue
surrounding the joints (Jenkins, 1951).
Proprioception

A proprioceptor is a sense organ for detecting the posi-
tion and spatial relations of a muscle and is located in the
muscles or tendons. Proprioception is generated within the
body from kinesthetic sensations and sensations of equili-_I
brium or balance or of any deep sensation of muscle and joint
position (Gray and Wise, 1959: Chusid and McDonald, 1967; and
Zemlin, 1968). Information from these proprioceptors is
transmitted to the central nervous system. ”This is the

principle of feedback whose essential machinery is the

5
stretch reflex and whose governing centers are, to an appre-
ciable extent, below the cerebrum, making these reflexes
basically unconscious” (Kaplan, 1960, p. 9).

Kinesthesis involves consciousness of muscle movement,
position, and tension (Shelton, Arndt, and Hetherington,
1967). Consequently the term ”kinesthesis" is probably more
appropriate than ”prOprioception” for oral perception since
the former term allows reference to sense of position.§ng
movement.

Stereogposis

Etymologically, the word derives from two Greek words:
sterio, solid, and osis, knowledge. manual stereognosis
perception is the ability to recognize, without the visual
sense, the size, weight and shape of objects. Stereognosis
is not a separate sense, but is a combination of the senses
of touch, spatial discrimination, cutaneous localization, and
kinesthesis (Best and Taylor, 1961). Stereognosis requires
the integrity of the central integrating processes of the
cerebral cortex (Chusid and McDonald, 1967; and Shelton et
al., 1967).

- Oral Stereognosig

Within the oral cavity the synthesis of different sensa-
tions, particularly kinesthesis and touch, is referred to as
oral stereognosis (McCall, 1969). Obviously this is a com-
plex perception involving not only touch and kinesthesis, but
also a higher degree of neural integration than the basic

senses. The speech pathologist is interested in oral

6
stereognosis since it may prove to be a sensitive indicator
of the '. . . complex oral somesthetic feedback which is an
essential part of the sensory-motor process by which speech
is produced” (Aungst, 1965, p.3).

If a person is unable to perceive and identify the form
of an object through oral manipulation, the appropriate term
is astereognosis regardless of whether the deficit is of an
organic or functional nature (Woodford, 1967). Avoiding the
term oral stereognosis, Moser, LaGourgue, and Class (1967)
use the term "lingual form perception" and suggest that a
deficiency here may be an indication of delayed development
or ”organic disintegration of faculties” resulting in the
hindrance of normal speech development (p. 244).

Theoretical Considerations on Oral Stereognosis

Many of the reported studies on oral stereognosis have

 

discussed speech production in terms of the feedback theory
described by Fairbanks (1954). The Fairbanks' model depicted
speech production as analogous to a servosystem which could
be regulated by automatic controls. In his system, Fairbanks
theorized that the speech output is monitored by a control
mechanism, where the output is compared with the input. Then,
the output producing device is manipulated so that the out-
put will have the same functional form as the input. Thus,
the speaker monitors his output by reference to how an utter-
ance sounds and fgglg when it is produced (Fairbanks, 1954,

p. 135).
If Fairbanks' servomechanistic (or closed-loop) theory

7

of speech control is valid, than speech under conditions of
neurosensory deprivation should be more seriously disturbed
and less intelligible than has thus far been demonstrated.
Schliesser and Coleman (1968) reported a study in which five
normal-hearing male subjects were required to read sentences
under the condition of auditory masking and reduction of tac-
tile sensation by anesthetization of the oral area. The judg-
ment of the investigators was that, under this condition, the
intelligibility of the speech was adequate and that the speech
was less defective than a ”moderate” clinical speech problem.
Schliesser and Coleman concluded that, at least for the short
term, an individual can speak satisfactorally in terms of
accuracy of articulation, rate of speaking, and inflection in
the absence of auditory or tactile sensation.

In a similar, though informal, experiment five subjects
read a test passage and made spontaneous remarks, while de-
prived of auditory and tactile feedback. The results of this
experiment indicated that although speech was I"very disorgan-.
ized' in the absence of auditory and tactile feedback, it was
still intelligible (Ladefoged, 1967).

On the other hand, an open-loop theory of speech control,
postulating no dependence on sensory feedback, would presupr
pose no change in articulatory accuracy under the same condi—
tions. Consequently, experimental results would tend to
support not a closed-loop 2;,0pen-loop system, but rather one
which indicated that precision in articulation is dependent

on a combined open-100p and closed-loop system. Scott and

7

of speech control is valid, then speech under conditions of
neurosensory deprivation should be more seriously disturbed
and less intelligible than has thus far been demonstrated.
Schliesser and Coleman (1968) reported a study in which five
normal-hearing male subjects were required to read sentences
under the condition of auditory masking and reduction of tac-
tile sensation by anesthetization of the oral area. The judg~
ment of the investigators was that, under this condition, the
intelligibility of the speech was adequate and that the speech
was less defective than a ”moderate” clinical speech problem.
Schliesser and Coleman concluded that, at least for the short
term, an individual can speak satisfactorally in terms of
accuracy of articulation, rate of speaking, and inflection in
the absence of auditory or tactile senSation.

In a similar, though informal, experiment five subjects
read a test passage and made spontaneous remarks, while de-
prived of auditory and tactile feedback. The results of this
experiment indicated that although speech was ”very disorgan-—
ized' in the absence of auditory and tactile feedback, it was
still intelligible (Ladefoged, 1967).

On the other hand, an open-loop theory of speech control,
postulating no dependence on sensory feedback, would presupr
pose no change in articulatory accuracy under the same condi-
tions. Consequently, experimental results would tend to
support not a closed-loop g; open-loop system, but rather one
which indicated that precision in articulation is dependent

on a combined open-100p and closed-loop system. Scott and

8

Ringel (1971a) explain that the speech mechanism
. . .Operates in response to autonomous motor

commands (or target specifications) which are largely
manner types of instructions. Having issued such in-
structions, however, the speech mechanism calls for
certain closed-100p refinements which are particularly
prominent for phonemes involving precise types of api-
cal and blade configurations. such as sibilants and the
consonant /e/; Information from oral receptors appears
to be a necessity for the successful execution of cer-
tain labial, apical and blade refinements which are more
important for some phonemes than for others.

(1» 815)

Fairbanks (1954) recognized auditory and tactile-
proprioceptive sensory systems Operating to monitor speech
production. He theorized that the control system was pri-
marily influenced by auditory feedback, whereas the tactile-
proprioceptive (or somesthetic) afferent system was consi-
dered to be of secondary importance. Although Fairbanks could
not deny the possibility that the tactile-proprioceptive sys-
tem might supply information about the Operation of the speech
mechanism, he did suggest that this sense probably did not‘
supply the more refined information about speech output which
he assigned to auditory feedback. Ringel (1970) has offered a
modification of the servosystem, suggesting that tactile in-
formation about articulatory contacts made during the produc—
tion of ggmg consonants may not be crucial to the feedback
mechanism operating for speech and that theories about the
relative importance of feedback systems should consider inter-
action with age as an important factor. It is quite possible
that as a person matures, the feedback system which is pri-
marily important during the stage of speech acquisition is
replaced by a different system of feedback when speech

9

activities are stabilized (Ringel, 1970).

The progression from one type of feedback control to
another as an individual matures, has been stated clearly by
Van Riper and Irwin (1958), who maintained that the auditory
sense is primarily important as a check on the correctness
or incorrectness of speech during the stage of learning the
patterns of speech utterance. However, once these patterns
are learned and internalized, it is the tactile or kinesthetic
feedback which is of primary importance (Van Riper and Irwin,
1958).

As an illustration of the importance of tactile or kines-
thetic monitoring systems over time, sixteen children, ages
7-9, enrolled in speech therapy, were tested for articulation
competency and oral tactile perception over a nine month
period. The results showed a positive relationship between
articulation proficiency and oral tactile perception (Ruseello
and Lass, 1973). The authors did not state whether they con-
sider the observed improved scores a function of maturation or
administration of therapy since there was no control group of
subjects. On the other hand, Shelton et a1. (1973) demonstra-
ted that the relationship which exists between oral sensation
and articulation competency did not indicate that manipulation
of one variable is effective in influencing the other.

Drawing a parallel from the sense of hearing, Hardy (1970)
has noted that auditory discrimination, which appears to be an
imprecise skill in the young child, improves as a function of
ago. That is, with increasing age, the auditory monitoring

‘10
system (error-detector) imposes progressively narrower limits
on the latitude of allowable error. Hardy has suggested that
a similar pattern of development is likely for tactile-
proprioceptive networks.

As the sensori-motor system improves its ability to
reproduce the signal that its auditory error-detecting
system is perceiving, the tactile and proprioceptive pat-
terns become more restricted and, thus, learned through
the less variable muscular behavior. Eventually, then,
those tactile-proprioceptive patterns will become rela-
tively fixed as the precision of the speech- reducing
musculatures stabilize. (Hardy, 1970, p. 62
In keeping with the foregoing discussion several inves-

tigators (Ringel, Burke and Scott, 1968; Robertson, Fucci and
Fokes, 1969; Fucci, 1972; and Shelton et al., 1973);have.found
that adult subjects showed decreased oral sensitivity in pro-
portion to the severity of articulatory problems. Other in-
vestigators (Aungst, 1965: Looks, 1969; Arndt et al., 1970b;
and Madison and Fucci, 1971), however, found that when child—
ren were the subjects there was no reliable relationship
between articulation errors and performance on tests of oral
stereognosis.

Several studies (Shelton et al., 1967; Arndt et al.,
1970a: Ringel, 1970; and Ringel et al., 1970b) have shown
that increasing age, or maturation in articulatory ability,
plays an important role in the proficiency of an individual's
use of oral stereognostic skills. Ringel (1970) has suggested
that in the adult the motor abilities and oral cavity size are
more fully developed than in the child, permitting more effi-

cient oral palpation of the stimulus forms.

11
Relatige Sensitivity of QralfStructurgg
Although the oral cavity consists of many different
structures, it performs uniquely as a single sensorimotor
organ: and it is within this organ that the highest sensori-
motor integrations are achieved (Bosma, 1967). Lass et al.
(1972a) tested the sensitivity of lips, tongue and finger tip
'since these areas of the body surface are the most sensitive
to touch (Kenshalc, 1971). They found that, within the limits
of their study, the tongue tip showed the most sensitivity
and the tongue dorsum and lower lip showed the least sensiti-
vity. Also midline regions of the oral structures were more
sensitive than the lateral margins; and some difference in
sensitivity existed between left and right sides of these
structures, although these lateral differences appeared
random and unrelated to handedness (Rutherford and McCall,
1967; McCall and Cunningham, 1971; and Lass et al., 1972a).
Other studies have consistently reported that of all the oral
structures, the tongue tip is the most sensitive and shows
the least variability to light touch and two-point discrimi-
nation (Grossman, 1964 and 1967: Gibson, 1967; Henkin and
Banks,.l967: MOCall,Hl9693 Fucci and Robertson, 1971: Kenshalo
1971; and Lass et al., 1972b). Moser et a1. (1967) have noted
that the tongue is a midline structure with half left and
half right (double) innervation. Therefore, as the tongue
becomes narrower towards the tip, the nerve endings become
proportionately more numerous resulting in the great sensiti-

vity of the tip of the tongue.

12

The two-point discrimination task referred to above has
been employed as a method for establishing a threshold of
tactile sensitivity. The two-point threshold is lowest at the
point of the tongue tip, where clear discrimination between
two points measured 1 mm. By comparison, the two-point
threshold for some parts of the back, thigh or upper arm
measured 68 mm (Woodworth, 1938: Bosma, 1967: and Paine,
1967). The perception of the difference between one and two
points is not clear-cut, but rather a progression through
stages: point, line, circle, oval, dumbell, and so on, before
two distinct points are recognized (Jenkins, 1951: and McCall,
1969) .

Another measure of cutaneous sensitivity is the pressure
threshold. Referring to an experiment by von Frey (1894),
Woodworth (1938) reports that the stimulus threshold for pres-
sure on the tip of the tongue is 2 grams/mmz.

It is evident, therefore, that the tongue tip is of para-
mount importance in oral sensitivity and manipulative ability
for study of the skills involved in oral stereognosis (Ringel,
1970)..

Intra—Oral Discrimination Versus Visual
matching Taskg

In oral stereognosis testing two principle methods which
have been employed require a subject to (1) identify a form in
the mouth by pointing to a form or picture of a form on a
visual display or (2) make a Psame” or ”different" decision
about a pair of forms examined intra-orally. Bosma (1967) has

noted that the hand is most sensitive tactually at the finger

12

The two-point discrimination task referred to above has
been employed as a method for establishing a threshold of
tactile sensitivity. The two-point threshold is lowest at the
point of the tongue tip, where clear discrimination between
two points measured 1 mm. By comparison, the two-point
threshold for some parts of the back, thigh or upper arm
measured 68 mm (Woodworth, 1938: Bosma, 1967: and Paine,
1967). The perception of the difference between one and two
points is not clear-cut, but rather a progression through
stages: point, line, circle, oval, dumbell, and so on, before
two distinct points are:recognized (Jenkins, 1951: and McCall,
1969).

Another measure of cutaneous sensitivity is the pressure
threshold. Referring to an experiment by von Frey (1894),
Woodworth (1938) reports that the stimulus threshold for pres-
sure on the tip of the tongue is 2 grams/mmz.

It is evident, therefore, that the tongue tip is of para-
mount importance in oral sensitivity and manipulative ability
for study of the skills involved in oral stereognosis (Ringel,
1970) ..

Intra—Oral(Discriminatipn Versus Visual
matching Taskg

In oral stereognosis testing two principle methods which
have been employed require a subject to (1) identify a form in
the mouth by pointing to a form or picture of a form on a
visual display or (2) make a teams” or "different" decision
about a pair of forms examined intra-orally. Bosma (1967) has

noted that the hand is most sensitive tactually at the finger

13
tips and that a comparable arrangement applies to the mature

human mouth. The tongue probes with its very sensitive tac-
tile tip within the mouth which is lined with receptor-rich
walls like a “chambered sensorium” similar to the eye or inner
ear. Within the mouth, the tongue measures and manipulates,
using a reference of dimensions and meaningful measurements
unique to the oral cavity. The sensations the tongue receives
are relayed to the nervous system in terms of oral anatomical
relationships. 0n the other hand, the fingers and the eye
receive sensations in terms of the geometric relations of the
external world: and information received through the hand or
the eye is conveyed to the nervous system in that frame of
reference (Bosma, 1967, p. 351).

Recognizing the probability of different kinds of infor-
mation being conveyed by two different modalities, Ringel et
a1. (1968) expressed concern about the confusion which may
result from the intersensory approach in testing oral stereo-
gnosis. Therefore, these authors suggested that if an eXperi-
menter is attempting to obtain information about the tactile
modality in the oral cavity, his measurements must be limited
primarily to that modality in order to avoid the contamination
which may result from involving other sensory channels. such
as vision. La Points and Williams (1973) have also shown that
some subjects will perform better with a unimodal presentation
than with a presentation involving more than one sensory
modality.

In an attempt to decide on a method yielding consistent

14

performance in oral stereognosis, Lass, Tekieli, and Eye
(1971) compared an intra-oral discrimination task with an
inter-sensory matching procedure. These investigators em-
ployed 30 female subjects who exhibited normal hearing, speech
articulation, neurological history, superficial tactile sen-
sation, oral cavity structure, and vision. The authors found
that 21 of their subjects made fewer errors on the visual
matching task than on the intra-oral discrimination task.
They hypothesized that there was a memory factor involved;
this hypothesis was partially supported by their subjects'
introspective statements that they performed poorer because
they had had so little experience in the discrimination task.
In their discussion, the authors noted that their procedure
was different from that of Ringel et a1. (1968) who had
found consistent results on the intra-oral discrimination
task. One of the differences between the Lass et a1. and
Ringel et al. studies was that the former investigators used
eleven forms instead of ten, as used by Ringel et a1. As
pointed out by Torrans (1972), the additional form used by
Lass et al. was a triangle, and it is significant to note that
the largest number of errors made under both conditions
(intra-oral discrimination and visual matching) involved the
triangular shapes (Lass et al., 1971).

Lass, Tekieli, and Eye expressed surprise at the results
of their eXperiment since the discrimination task, pgig;
fggig, would be expected to prove easier than visual matching.

Whereas in the former case the probability of making a correct

15
choice by chance alone was 0.5, in the latter case the pro-
bability of such an occurrence was only 0.2. In two recent
investigations the question of type of response has been
further studied. Torrans and Beasley (1973) compared the
performance of forty young adults on different combinations
of form sets, two oral form retention times (five seconds
and unlimited) and two types of responses (a visual matching
task and an intra-oral discrimination task). The results of
this study indicated that scores on a test of oral stereo-
gnosis varied significantly depending upon the methodology
employed. One of the results was that the intra-oral discri-
mination task was easier and yielded more consistent findings
than the visual matching task. Bain (1973) investigated
'subject performance on the task of intra-oral discrimination
and found more consistent results than the visual matching
task, thereby corroborating the results reported by Torrans
and Beasley (1973).

Thus contradictory reports are found in the literature;
some investigators contending that the preferred method of
oral stereognostic testing is intra-oral discrimination,
whereas others have found better results by employing the
visual matching method. Based upon their results, Torrans
and Beasley (1973) have speculated that if Lass et a1. (1971)
had used the same set of ten forms as used by Ringel et al.
(1968) and Torrans and Beasley (1973). their results would
have supported the claims made for the intra-oral discrimina-

tion task and would have paralleled the results reported by

16

Torrans and Beasley.

In a study comparing the methods employed in testing
oral stereognosis (Torrans, 1972),.a lack of consistency in
results was traced to failure to use standardized methodology
in test construction, test administration, and scoring and
reporting results, to mention some of the more important
uncontrolled variables. As expected, the intra-oral form
discrimination task, involving no intermodality confusion
factors, yielded the most consistent results (Torrans and
Beasley, 1973). Consequently, this method will be followed in
the present study. Of the many parameters examined in the
study of oral stereognosis, time intervals and duration of
stimuli have received only casual consideration when reporting
the use of geometric forms. Sometimes the subject has been
given unlimited time for oral exploration of the form, whereas
in other experiments the subject was limited to a maximum
duration of five seconds for the same task (Torrans, 1972).

The temporal factor in auditory perception has been in-
vestigated by Beasley and Shriner (1973). In this study, the
authors covaried stimulus duration and interstimulus interval
ratios of sentential approximations. The results of this
study indicated that temporal factors were important in audi-
tory perceptual processing, the stimulus duration being more
crucial for perception than the inter-stimulus interval.

To this investigator's knowledge, the within-pairs
temporal interval and between-pairs temporal interval have not

been subjected to critical examination. Arndt et al. (1970b)

17

proposed a I'pure" measure of oral stereognosis that required
a subject to discriminate between a pair of simultaneously
presented forms (attached to a single wand) which the subject
could explore orally. It was thought that this technique
would provide a unimodality task while avoiding the problem
of short-term memory (a problem which.might arise if two
items of a pair were presented successively with a five
second interval). However, the authors failed to consider
another problem, namely the differential sensitivity within
the mouth. This problem might arise if the two items of a
pair of forms, presented simultaneously, were not available
at the same time to the most sensitive part of the tongue.

The question of short-term memory was studied by Lass and
Clay (1973). They found that there was no significant dif-
ference between the conditions of simultaneous presentation
of forms and pairs of forms presented with a five second
interval. This would indicate that memory (at least up to
five seconds) is not a factor which would make a task of
intra-oral discrimination more difficult than when the pair
of items are presented simultaneously. The authors suggest
that the reason for this may be the differential sensitivity
of the various parts of the mouth, especially the tongue
which is most sensitive at the midline and at the tip.

The authors suggest that further research should look at
this question of time intervals to determine whether intervals
of time longer than 5 seconds will have an adverse effect on

performance.

18

Torrans and Beasley (1973) found that another factor
contributing to score variability of oral stereognostic meas-
ures was form retention time which interacted with answer
type and form set. This variable was limited to a five second
retention time and unlimited retention time for manipulation
of the geometric forms. In order to include an oral stereo-
gnosis test in the clinical setting, it would be useful to
know whether, and to what extent, temporal variables are
important.

Statement of the Problem

The possibility exists that temporal factors which have
been shown to be significant in auditory perception (Beasley
and Shriner, 1973) may also play an important role in oral
sensation and perception. Several temporal factors may
contribute to differential oral sensory responses: (l)intra-
oral duration of stimulation by a form, (2) interval between
the two items within each pair, and (3) interval between
presentation of pairs of items. (In future references to
these three conditions, they will be abbreviated as follows:
(1) intra-oral duration, (2) within-pairs interval, and
(3) between-pairs interval.)

The purpose of the present investigation is to eXplore
the effect of varying the temporal factor in three ways as
indicated above, noting the manner in which these variables
interact with one another. Specifically, the following ques-
tions will be investigated:

(1) Will intra-oral durations of 3, 5, and 7 seconds

(2)

(3)

19

result in different oral stereognostic scores for
young adult subjects with normal articulation and
normal hearing?

Will within-pairs intervals of 3, 5, and 7 seconds
result in different oral stereognostic scores for
young adult subjects with normal articulation and
normal hearing?

Will between-pairs intervals of 5, 7, and 9 seconds
result in different oral stereognostic scores for
young adult subjects with normal articulation and

normal hearing?

CHAPTER II
EXPERIMENTAL PROCEDURES

This chapter provides details concerning the subjects,

experimental conditions, and experimental procedures employed.
Subjects

The subjects of this study were 45 young adults (16 -
30 years of age) having no history of neurological or sensory
defects. All subjects were required to (1) pass a pure tone
audiometric screening test at 500, 1000, and 2000 Hz at 25 dB
(re ANSI), (2) exhibit normal conversational speech articula-
tion as judged by a speech pathologist, and (3) refrain from
smoking, eating or drinking anything except water for two
hours prior to being tested. In addition, all subjects were
blindfolded during the testing session to eliminate visual
cues.

Experimental Conditions

The stimuli employed in this investigation were ten geo-
metric plastic forms known as the Ringel Forms. This set of
forms was chosen because of its demonstrated discriminatory
effect on varying degrees of subject sensitivity to oral sen-
sation and perception (Torrans and Beasley, 1973).

All #5 subjects received pairs of forms at the three

20

.1;

21
betweenwpairs intervals (5, 7 and 9 seconds). Of these #5
subjects, 15 were randomly assigned to the three-second intra-
oral duration condition; 15 were randomly assigned to the five-
second condition: and 15 were randomly assigned to the seven-
second condition. The three within-pairs intervals were
crossed with intra-oral durations so that for each intra-oral
duration, five subjects were randomly assigned to the three-
secend within—pairs interval condition, five subjects were
randomly assigned to the five-second condition and five
subjects were randomly assigned to the seven-second condition.
The order of presentation of the pairs of forms in each con-
dition was randomized for each subject.

Every form was paired with itself and with every other
form in the set. The Ringel set of forms contained ten items.
Therefore, 55 pairings were possible. All possible pairs of
forms were presented in random order to every subject.

Epocedures

By reference to Appendix B, showing the data matrix for
this study, it is evident that there were twenty-seven treat-
ments employed in the total experiment. These treatments
correspond to sequences of time intervals. For example, the
first five subjects received the first three treatments or
temporal sequences, and so forth, so that 45 subjects received
twenty-seven treatments. In order to insure accurate meas-
urements of time durations and intervals, it was decided to
employ auditory cues. Twenty-seven tape loops corresponding

to the twenty-seven treatments were constructed in the

,22
following manner. The time intervals were marked on the tape
by recording a 500 Hz pure tone which was on continuously for
the temporal duration that the first of a pair of forms was
on the tongue. This was followed on the tape loop by an in-
terval accompanied by no auditory stimulus for the appropriate
within-pairs interval between the first and second of a pair
of forms. The end of this interval was marked on the tape
loop by recording a 400 Hz pure tone which was on continuously
for the temporal duration that the second of a pair of forms
was on the tongue. At the end of this tone there followed an
interval accompanied by no auditory stimulus for the appro-
priate between-pairs interval marking the interval from one
pair to the next pair of forms. When the twenty—seven tape
loops were finished each one was checked for accuracy. It was
found that all time intervals were correct to 1/2h sec. Each
loop was then re-recorded 55 times on a tape cassette.

During the testing sessions these tape cassettes were
played back and provided auditory cues to the examiner ena-
bling him to adhere to the correct time durations and inter- a
vale as he administered the stimuli. Since the subjects were
blind-folded, the same auditory signals were cues to them
indicating when they should be prepared to receive a form on
the tongue. Two equal rest periods were allowed between the
three treatments for each subject. Since an essential part
of the experiment involved varying the time sequences for
groups of five subjects, these two rest periods were necessar-

ily adjusted from group to group in order to achieve a total

23
time of ninety minutes for the testing session for each
subject.

Before each testing session began, written standard
instructions were given to each subject to read (Appendix 0).
Any part of the instructions which was not clear to an indi-
vidual subject was explained in greater detail. A maico
portable audiometer (model MA-ZB), which had been calibrated
in accordance with ANSI norms, was used to test the subjects'
hearing. Subjects were then allowed five minutes to examine'
the Ringel set of forms before testing began. This orienta-
tion involved both visual and oral examination of the forms.
When the subject was ready for the testing session, he was
blind-folded, the examiner put on a new disposable examination
glove of the type used by physicians, and the testing session
began with the examiner and subject listening to the cassette
tape for auditory cues as described earlier in this chapter.

When the 500ih5tone was on the subject opened his mouth
and slightly protruded his tongue while the examiner placed
the first of a pair of forms on the tip of the tongue for the
duration of the tone. The subject was allowed to perceive the
shape of the form only through passive use of the tongue.

That is, as the form was placed on the tip of the tongue, he
was allowed to push upward on the inferior surface of the form
but no manipulation of the form was allowed. At the end of
the tone the form was removed from the tongue, turned over

and replaced in its proper place on the tray. After the
within-pairs interval, the hoorhstone signaled the duration

. 24
for presentation of the second of the pair of forms which was
perceived by the subject in the same manner as the first form.
At the end of the 400 Hz signal the form was removed from the
tongue, turned over and replaced on the tray. During the
ensuing between-pairs interval the subject told the examiner
whether the two forms were the same or different. At the end
of this interval the 500 Hz tone signaled the presentation of
the first of the next pair of forms. Thus, the procedure was
repeated for the remainder of the 55 pairs.

After a rest period the next temporal sequence was pre-
sented for the second treatment for that subject. This was
followed by a second rest period and the third treatment for
that subject. The subjects received no feedback on the core
rectness or incorrectness of their responses until after the
testing was finished.

A list of the pairs of forms to be presented was prepared
for each treatment for each subject. Forms were listed by
number on the listsand on a specially prepared tray on which
the forms were placed. Each subject's responses were recorded
on the list for his individualized random order of presenta-
tion. The forms and the tray on which they were placed were
sterilized in iSOprOpanol (CHBCHOHCHB) and rinsed in water
prior to presentation to each subject. Appendix E contains
an illustration of the arrangement of the equipment used in

conducting the experiment.

CHAPTER III
RESULTS

An analysis of variance using arcsin transformations was
performed upon the raw scores obtained for the several vari-
ables under study (the three levels of intraqoral duration,
the three levels of within-pairs interval of time, and the
three levels of betweenepairs interval of time) and their
respective interactions. Significant main effects were found
for the factors of within-pairs interval and between-pairs
interval. There was no significant main effect associated
with the intra-oral duration factor. Mean data for all
variables and interactions can be found in Table l. A com-
plete analysis of variance table can be found in Appendix A.

are o'rwmr‘rer‘enteevam Offlithin'tl’eW

There was a significant main effect (P = #.22, df = 2,

p <'0.05) for the factor of within-pairs interval. As can be
seen in Figure 1, the three-second interval yielded the least
number of errors overall, followed by the five-second inter-
val, and the seven-second interval, respectively. Post hoc
procedures revealed a significant difference from the five-
second to the seven-second within-pairs interval (t a 2.6,

df a 1h, p <20.05) and from the three-second to the seven-

25

26

Table 1. Mean error scores for each level of each factor
under study (Intra-Oral Duration, Within-Pairs
Interval, Between-Pairs Interval).

 

vj W W v—V v—W. "r'

 

filj vw v —v ww—

 

 

 

 

13332321 "iifiii‘fiirs ”1°33???"

'1' w_ I“ 3"sec.fi'f "'VIsec. * 9—538.

3 sec. 2* 7.2 518 , 5.2

3 sec. 5 sec. 4.6 4.0 5.0

7 sec. 7.0 7.2 7.2

3 sec. 4.6 3.4 2.6

5 sec. 5 sec. 6.4 5.6 3.6

7 sec. 6.0 6.4 5.8

3 sec. 4.6 3.4 3.4

7 sec. 5 sec. 5.0 4.4 4.2

7 sec. 6.6 5.4 5.6

 

Average number of errors

 

\
\

l
\

 

27

1 i.

 

Figure 1.

3 5

Time (sec.)

main effect of the within-pairs interval.

28
second within-pairs interval (t = 3.19, df = 14, p«<.0.05).
Thus different within-pairs intervals did result in signifi-

cantly different scores.

Effect ofpifferent4gevels of Between-Pairs Interval
There was a significant main effect (F = 3.18, df = 2,

p‘C 0.05) for the factor of between-pairs interval. As can be
seen in Figure 2, the between-pairs interval of five seconds
yielded the greatest number of errors overall followed by the
seven-second and nine-second between-pairs intervals respec-
tively. Post hoc procedures revealed a significant difference
between the five-second and nine-second between-pairs inter-
vals (z a 1.90, p‘< 0.05). Thus different between-pairs

intervals resulted in significantly different scores.

Effect of'Different_;evels ofwlntra-Oral Duratiggg

The difference between the three levels of intra-oral
durations (three, five, and seven seconds) was not statisti-
cally significant (F = 1.62, df = 2, p >’0.2). As can be
seen in Table 2, the three-second intra-oral duration yielded
the greatest number of,errors overall, followed by the five-
second and seven-second intra-oral durations respectively.
Although not significant, there was more difference in number
of errors between the three-second and five-second durations

than between the fiveusecond and seven-second durations.

Average number of errors
u\

 

 

Figure 2.

29

v—

5 7
Time (sec.)

Main effect of the between-pairs interval.

§_.

30

 

 

 

 

 

 

 

 

Table 2. Mean number of errors as a function of Intra-Oral
Duration
Intro-Oral Duration Number of Errors
3 seCe 5'9
5 sec. “-9
7 sec. 4.7
Table 3. Percentages of errors made on pairs of forms from
the Ringel Set
1 23.0
2 52.0 11.0
3 00.7 00.7 08.0
'4 01.5 00.0 43.0 15.0
5 03.0 03.0 00.7 06.7 15.0
6 00.0 00.0 02.2 08.0 18.5 17.7
7 02.2 00.7 00.7 09.6 26.0 41.5 27.4
8 02.2 01.5 00.7 00.7 07.4 00.0 21.5 11.0
9 00.0 00.0 00.7 01.5 06.7 20.0 06.7 00.0 19.0
10 00.7 00.7 00.0 00.0 00.7 04.4 00.7 00.7 46.0 27.4
1 2 3 4 5 6 7 8 9 10

 

31
Difficulty in Discriminating Pairs of Form;

The degree of difficulty in discriminating pairs of forms
is reported in Table 3. This table indicates for each pair of
forms the percentage of errors made during the complete
experiment. It may be noted that the four most difficult
pairs of forms (1-2, 9-10, 3-4, and 6-7) account for 35% 0f
the errors made during the experiment. The next fifteen
pairs, including the ten identical pairs, accounted for 52%
of the errors; the next twenty-seven pairs accounted for only
13% of the errors and nine pairs were always correctly

discriminated.

CHAPTER IV

DISCUSSION

This study compared the effects of varying intra-oral
duration, within-pairs interval and between-pairs interval
on the number of errors made by normal young adult subjects
on an oral stereognosis task. All subjects (N = 45) received
twenty-seven treatments, including all possible combinations
of the three intra-oral durations (3, 5 and 7 seconds),
three within-pairs intervals (3, 5 and 7 seconds), and three

between-pairs intervals (5, 7 and 9 seconds) under study.

lgtra-Oral Duration

The questions of how long a duration is necessary for the
tongue-tip to perceive the shape of an object has received
some attention by Torrans and Beasley (1973). In this present
study intra-oral duration was not a significant factor in
score variability. So that whether the duration was three,
five or seven seconds, the subjects seemed to achieve compar-
able scores. This result corroborates that reported by
Torrans and Beasley (1973) who found that score variability
was not affected by form retention time alone. In their study

there were two levels of form retention time, five seconds and

32

33
unlimited time. They suggested that a shorter or longer time

limit than the five seconds level in their study might produce
a significant main effect. Within the limits of this study,
it would seem that this question has been answered negatively.

Torrans (1972) found that when some of her subjects were
given unlimited time for intra-oral duration for some of the
forms, they needed only two to four seconds for perception.
This was found to be the case in the present study also.

Since only one answer type (a same-or-different discrimina-
tion) was utilized in this study, an additional observation
may be made. The first of a pair of forms was usually made
the object of concentration for the full duration allowed.
When the second form was placed on the tongue, however, the
subject knew that he only had to decide whether it was the
same or different from the first and he tended to need consi-
derably less perceptual time to make this decision.

The form which was the easiest to perceive was the true
square (form number 3). The size of this form seemed to be
significantly larger than any of the other forms so that it
proved to be relatively easy to identify. 0n the other hand,
the small rectangle (form number 5) appeared to be the most
confusing of the forms. Subjects reported that the corners of
the rectangle were not clearly perceived by the tongue.

Perception through passive use of the tongue was found to
yield certain advantages:

1) Subjects did not complain of a soreness or irritation

of the tongue.

34
2) Subject technique for perception of the forms was
uniform.
3) The experimenter retained complete control during

the presentation of the forms.

Within-Pairs Interval

The results of this study have a direct bearing on the
question of short-term memory and the studies of Lass and
Clay (1973) and Arndt et al. (1970b). The results of the
study by Lass and Clay led them to conclude that memory (at
least up to five seconds) was not a significant factor in oral
stereognosis. They studied the effects of presenting the
forms in pairs simultaneously and with five seconds between
two items of a pair of forms. They recognized that their
results may have been confused by the fact that in the simul-
taneous presentation it was not possible for both of the forms
to be centered in the midline of the tip of the tongue. As a
result one of the forms was usually positioned lateral to the
midline, while the other form was usually on the other lateral
portion of the tongue.

In the present study the indication is that when the
forms are presented to the same part of the tongue (the tip)
the error scores will increase as the within-pairs interval is
increased. This suggests that short-term memory is indeed a
significant factor in a discrimination task in a test of oral
stereognosis, and that the best discrimination performance can
be achieved with a relatively short within-pairs interval.

What has been said above about the limitations inherent

35
in a simultaneous presentation of forms applies to the study
by Arndt et al. (1970b). Probably these investigators were
justified in their concern for a ”pure” measure of oral
stereognosis in which only the oral tactile sense was percep-
tually involved. However, in the simultaneous presentation
of a pair of forms, they also failed to consider the differen-
tial sensitivity of the oral cavity in general and the tongue
in particular.

Because of the above-mentioned problem associated with
simultaneous presentation of forms, it seems that the inter-
ests of consistency and test—retest reliability may be served
best by presenting pairs of forms with a short within-pairs
interval.

In auditory perceptual processing, Beasley and Shriner
(1973) found that temporal factors were important variables.
As stimulus duration and interstimulus ratios of sentential
approximations were covaried it was found that the stimulus
duration was more crucial than the interstimulus interval for
perception. Comparing these results with the results of the
present study, it may be stated in general terms that temporal
factors are important variables in both auditory and tactile
perceptual processing. Specifically, whereas stimulus dura-
tion was shown to be significant in auditory perception, oral
tactile perception has been shown to be sensitive to the
interstimulus or within-pairs interval. This conclusion is
supported by reference to Figure 1.

The results of this study suggest that memory may very

36
well have played an important role in subject performance on
a test of discrimination between items of a pair of forms.
During the experiment those subjects who were tested with a
seven-second within-pairs interval often indicated uncertainty
when presented with the second of a pair of forms. These
subjects reported that their uncertainty was due to a short-
term memory problem or an attention problem. The attention
problem was more crucial as the testing progressed for an
individual subject. Especially was this so for those subjects
who received the longer within-pairs interval of seven se-
conds. The common complaint of such subjects was not fatigue,
but of boredom. It seems that with the seven-second within-
pairs interval, especially, subjects had a distinct problem
in attending to the task at hand. Norman (1969) very clearly
connects attention with memory, observing that an object
attended to may remain in the memory, whereas one inatten-

tively allowed to pass will leave no traces behind.

Differential Difficulty of Pairs of Forms

Since the same fifty-five pairs of forms as used.by
Torrans (1972) were also used in the present study it is
interesting to note some comparisons regarding the varying
difficulty of different pairs of forms. The four pairs of
forms which were most difficult in this study were 1-2, 9-10,
3-4 and 6-7. These same four pairs were also among the first
five most difficult pairs of forms in Torrans' study.

Rothk0pf (1957) conducted a study to provide a measure

37
of similarity among the signals of the International Morse
Code. The subjects of the experiment were exposed to pairs
of auditory Morse signals sent at a high speed and required
to indicate whether the two signals in each pair were the
same or idfferent. In this auditory task it was found that
the subjects sacred the highest correct ”same" discrimination
responses on the group of objectively identical stimulus
pairs.

The results of this present investigation involving the
tactile modality do not agree with the results of Rothkopf
involving the auditory modality. The nine pairs of geometric
forms which in this study were judged correctly all the time
by all the subjects were all composed of different stimulus
items. Those pairs of forms which were identical were grouped
together in the area of medium difficulty. The pair 3-3 was
discriminated correctly 92% of the time, and the pair 7-7 was
discriminated correctly 72.6% of the time (Table 3.). The
remaining eight identical pairs were found to have a degree of
difficulty in discrimination somewhere between these two per-
centages. These results, while differing from those reported
by Rothkopf, do corroborate the results reported by Torrans
(1972) in which nine of the identical pairs of forms were
found to be more difficult than thirty-nine of the different
pairs. In the present study the same nine identical pairs of
forms were found to be more difficult than thirty—eight of
the different pairs.

These two reported corroborations of the Torrans study

38
lend support to the view that the tactile sense is a uniQue
modality (Bosma. 1967) which must be studied independently
without bias from investigation of other modalities. The
results of that study indicate that oral tactile perceptual
processing is influenced by a unique set of categories which
do not necessarily conform to the categories which are mean-

ingful for visual or auditory perceptual processing.

Procedural Considerations
The Ringel set of ten forms used in this study were also

used by Ringel et a1. (1968) and Torrans and Beasley (1973).
It is interesting to note that these three studies are in
mutual agreement on the question of employing a unimodality
approach to oral stereognostic testing in preference to a
visual matching procedure. This finding assumes some impor-
tance when considered in view of the different results repor-
ted by Lass et a1. (1971). In this study a third triangular
form was added to the Ringel set of forms. Torrans and
Beasley have speculated that if Lass et a1. had omitted the
third triangular shape, their results would also agree with
the other studies cited above. This speculation has received
further support from the results of this study.

There is general agreement in the literature that of all
cutaneous surfaces in the mouth. the tongue-tip is the most
sensitive to touch (Grossman. 1964 and 1967: Gibson. 1967;
Rankin and Banks, 1967; McCall, 1969; Fucci and Robertson,
1967: Kenshalo. 1971; and Lass et al., 1972b). In the course

39
of this study. some subjects reported that the tip of the
tongue was very sensitive to the exact position of the forms
and that discrimination was best when two forms of a pair were

presented on exactly the same part of the tongue.

Considerations for Clinical Application

Many investigators have commented on the relationship
between speech articulation and the oral tactile and kines-
thetic monitoring systems (Van Riper and Irwin, 1958; Ringel,
1970. and Ruscello and Lass. 1973). These studies have indi-
cated that as a person matures the tactile and kinesthetic
sensory mechanisms increase in importance for monitoring
articulatory accuracy. When testing began, the subjects in
this study were usually doubtful about their ability to dis-
criminate between several of the forms. Thus. when the tee-
ting session finished, their performance, indicated by the
test results. surprised them. Most subjects acknowledged that
they did not expect their tongues to be so sensitive to the
fine differences between forms.

During the past decade much of the research in the area
of oral stereognosis has yielded information which could
eventually result in a practical tool for speech pathologists.
This present study may be considered another step in the
direction of presenting a test of oral stereognosis which
could be used with confidence in the assessment of an indivi-
dual's oral sensitivity to tactile and kinesthetic cues. If

a test is to be used in a clinical setting the results

40
reported at a given time and place should be understood and
should be amenable to replication at another time and place.
Therefore, there is a need for outlining detailed procedures
which may be easily understood and which control for as many
variables in the testing procedure as it is possible to
control. Clearly, in a test of oral stereognosis. the tem-
poral factors are important variables which should be con-
trolled. From the information obtained during this investi-
gation the following suggestions seem warranted for use with
the ten Ringel forms as applied in a same-or-different
discrimination task:

1) The intra-oral duration should be five seconds.

2) The within-pairs interval should be three seconds.

3) The between-pairs interval should be nine seconds.

It may be reasonably expected that the results of the
investigations into oral sensation and perception could yield
useful techniques in diagnosis and therapy for speech
pathologists.

In terms of the administration of a test of oral stere-
ognosis. as in any other test or measuring device used in
diagnosis. the clinician needs to become familiar with the
testing procedures. These are not difficult to understand
although care should be exercised in keeping to the correct
time intervals suggested above. The best method to insure
accuracy in the temporal sequences is the use of auditory
signals as suggested in the procedures of this study. If a
clinician intends to use this test for the first time, a

41

certain amount of practice time is recommended so that the
testing session may proceed smoothly. It may not be neces-
sary to administer all the fifty-five pairs of forms as used
in this experiment. Further research is needed to determine
which stimulus items may be omitted and which ones should be
included. The results of this study suggest that nine of the
pairs of forms, those which were never missed (Table 3), may
be redundant and perhaps these may be omitted from the test
as used in a clinical setting. Such a decision, however,
needs to await further research with pathological populations.

If the results of diagnostic testing of an individual
indicate a reduced sensitivity to tactile and kinesthetic
oral sensation and perception, this information may be used
by the speech pathologist as he plans for a program of thera-
py. Thus, more effective therapeutic techniques could con-
ceivably be devised in a rehabilitative program, emphasizing
subject recognition of correct placement of his articulators,

or training him to use compensatory techniques.

Considerations and Suggestions for Future Research

The results of this study have highlighted the impor-
tance of careful attention to the factor of time in the
administration of a test of oral stereognosis.

During the present investigation it was observed that
many subjects were confident about making a same-or-different
discrimination judgment after the second of a pair of forms

was on the tongue for a much shorter time than was required

#2
for the perception of the first of the pair of forms. A
comparative type of study could be conducted to test the
hypothesis that when presenting pairs of forms for discrimi—
nation, scores are unaffected by presenting the second form
for time periods shorter than used in presenting the first
form.

There are indications from Table 3 that some pairs of
forms may be eliminated from an actual test of oral stere-
ognosis without affecting the discriminating power of the
testing instrument. It will be noted that no errors were
recorded for nine pairs of forms and that only one error was
recorded for each of thirteen pairs of forms. The remaining
thirty-three pairs of forms may be sufficient to comprise an
adequate test of oral stereognosis. If this could be demon-
strated by experimentation the result would be an abbreviation
of the test. Such a result would be desirable since there
would be less possibility of a boredom factor as a confounding
variable in the subject's response.

In order to restrict perception to one modality. the
tactile sense, procedures in this investigation called for
a same-or-different discrimination type of task while exclud-
ing the visual modality. In this type of test, however, some
subjects reported a problem in being able to retain a clear
perceptual image of the first form for comparison with the
second of a pair of forms. Since the Ringel set comprises
only ten forms. it should be possible to perform a test of

absolute identification. In this case the above mentioned

43
prdblem associated with the within-pairs interval would be
eliminated, since a subject would be required to make an
identification response immediately after a form would be
removed from the tongue. In order for such a task to be pos-
sible, thorough familiarization with the forms would be
necessary before administering the test. Although this
familiarization procedure might be comparatively lengthy
(perhaps ten or fifteen minutes). the actual testing could
be much shorter than was the case in this present experiment.

Torrans and Beasley (1973) found that form set difficulty
was a significant factor in subject performance. Specifically
they found that the forms developed at Penn State were easier
for subjects to discriminate than those used by Ringel and
as used in this study. Thus, subject performance on one set
(Penn State Forms) may be expected to yield a minimum of
errors, whereas the other set (Ringel Forms) may be expected
to provide a more difficult task for the same subjects
(Torrans and Beasley, 1973).. To what extent this factor
interacts with temporal factors is as yet undetermined.

The subjects in this study were normal-hearing, normal-
articulating young adults. Further research needs to be
performed on subjects who exhibit different pathologies, such
as cerebral palsy, cleft palate, aphasia, or stuttering, to
mention a few.

There was not a significant main effect for intra-oral
duration in this study. This may suggest that different
durations should be applied in further investigations. It

44
would be practical to use durations as brief as 1 second
so that in further enquiries the eXperimenter could use
intra-oral durations of l, 3 and 5 seconds.

Another direction of inquiry is suggested by considering
the relative sensitivity of different areas of the oral
cavity. The tip of the tongue appears to be most sensitive
in a test of oral stereognosis as indicated in this and
previous studies. However, it would be helpful to know what
comparative information could be obtained as other interior
and exterior cutaneous surfaces of the oral cavity are stimu-

lated with geometric forms.

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n7

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APPENDICES

APPENDIX A

ANALYSIS or VARIANCE TABLE

51

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ema: , Haves
no.3 Nu N nonum
so.HH .mm H “chum
od. . No.a m mhwdmucmmzpmm

x whamaucaspaz x Hanomsch

on. No.m d mHHmQICmmzpmm
x muamaucanpaa

 

wm. um.m d mufimmucmmzpmm x Hmnomnch

mm. ma.oa : mnamg-canpaz x Hauomuqu

mo.va .ma.m Hm.NH m mnama-cmmspmm
molvm .mm.e mm.m: N muamaucanpfla
No.a nm.ua N HmuomapsH

m m m2 Hp cowvuaum> mo magnom

 

 

manna mocdauu> mo mwmhamc<

APPENDIX B

DATA MATRIX
SHOWING THE DESIGN OF THE STUDY

52

Data Matrix Showing the Design of the Study

Factors:

A-

w
I

O
I

U)
I

 

Intra-oral duration

A1 - 3 seconds, A2 - 5 seconds,-A3 - 7 seconds

Within-pairs interval
Bl - 3 seconds, B2 - 5 seconds, B3 - 7 seconds

Between—pairs interval
C1 - 5 seconds, C2 - 7 seconds, C3 - 9 seconds

Subjects

C1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

APPENDIX C

INSTRUCTIONS TO SUBJECTS

APPENDIX C

INSTRUCTIONS TO SUBJECTS

In this experiment the tactile sensitivity of the tip
of your tongue is being tested. To eliminate visual cues
you will be blindfolded. I shall place a geometric plastic
form on the upper surface of the tip of your tongue for a
few seconds, remove it for a few seconds and then place the
same or a different form on your tongue for a few seconds.
After removal of the second form you are to tell me whether
the two forms were the same or different. This process will
be repeated for many pairs of forms. During the presentation
of each form, you will be allowed to push upward with your
tongue, while I hold it, but you will not be able to manipu-
late the form in any other way.

After the first series of pairs of forms, you will have
a short rest. Then another series of pairs of forms will be
presented, followed by a short rest. A third series of pairs
of forms will be presented and this will complete your part
of the experiment.

In order to acquaint you with the tactile sensation of
the forms you will be given an orientation before the test
begins. During the orientation each form will be presented
on your tongue as you will feel it during the actual test.
Following the orientation, you will hear a tone. This is

your cue to receive the first form, and it is my cue to place

53

54
the form on your tongue. The form will stay on your tongue
for the duration of the tone. The second form will be presen-
ted when a second, lower tone is heard. The second form will
be on your tongue for the duration of the second tone. After
the second form has been removed, you are to tell me whether
the pair of forms were the same or different. This procedure

will be repeated throughout the whole test.

APPENDIX D
ACTUAL SHAPES AND SIZES
or THE RINGEL SET FORMS

55

 

A

 

A

 

   

1 2
.57 .A6
3 u 5
1.09 .85 .57
6 ' 7 8
.75 .67 .57
9 10
.50 .58

The actual shapes and sizes of the Ringel Forms. Under the
number of each form is a number indicating its mass in grams.

APPENDIX E
ARRANGEMENT OF EQUIPMENT
USED IN TESTING SUBJECTS

II'I‘

56

 

Arrangement of equipment used in testing subjects. The
subjects' chair my be seen behind the tray of forms.

APPENDIX F
THE FIFTY-FIVE PAIRS OF FORMS
USED IN THE EXPERIMENT

57

The fifty-five pairs of forms used in the experiment listed
in descending order of difficulty.

1 l-2 A g 23 1-7 A u
2 §'i° 3' 2 2’ $3 : ’
3 ' 30 II
t; 6-7 - : 31 l-b A I
5 7-7 . 32 2-8 A o
6 10-10 I- 0- 33 1,-9 I c-
7 5-7 I . 3),; 1-3 A I
8 1:; A A 332 1-10 A o.-
9 7 C C 2-3 ‘
10 6-9 - "' 37 2-7 A u
11 9-9 '- I' 38 2-10 A u-
12 5-6 ' " 39 3-5 I -
A 2*; :: :2 a :-
- A.
15 H: ' ' 1.2 3-9- I .-
I; 3:: ;: :: ti gii) II«I
- - a
18 1.1-? I a 1,5 7-10 . on
19 3.3 I I 1.6 8-10 . ..
20 h-6 I O ’47 1-6 A u
21 5-8 - 1.8 1-9 A -
22 h-S I - 1:9 2-h A I
23 5-9 I I" 552 2-6 : -
21; 7-9 . 'I 2"9 "
25 6-10 - - 52 3.10 I .—
26 1-5 A - 53 h-1o I -
27 2-5 A' I 514 6-8 - .
55 8-9' . "