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DEVELOPMENTAL STATUS AS A CORRELATE
OF PSYCHOPHYSIOLOGICAL MEASURES OF ATTENTION
IN EARLY INFANCE

presented by
STEVEN G l TTERMAN

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DEVELOPMENTAL STATUS AS A CORRELATE
OF PSYCHOPHYSIOLOGICAL MEASURES OF ATTENTION
IN EARLY INFANCY

BY

Steven Gitterman

A THESIS

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

MASTER OF ARTS
Department of Psychology

1979

ABSTRACT

DEVELOPMENTAL STATUS AS A CORRELATE 0F PSYCHOPHYSIOLOGICAL MEASURES
OF ATTENTION IN EARLY INFANCY

BY

Steven Gitterman

The present study utilized a recent psychophysiological model of atten-
tion, the two component model, to assess the relationship between
infants' relative developmental status and sustained cardiac atten-
tional responsitivity. A separate analysis also was done to see if
the model would differentiate cardiac responses to stimuli previously
shown to elicit differential amounts of prolonged looking behavior.
Results indicated strong support for previous studies showing cardiac
orienting responses to nonaversive auditory and visual stimuli. How-
ever, there was little evidence distinguishing between high and low
developmental status groups (assessed by the Bayley Scales of Infant
Development). Similarly, cardiac responsitivity was unrelated to
infant looking behavior. Infants' cardiac responses did discriminate
between an aversive and a nonaversive auditory stimulus. Methodolog-
ical factors which may have contributed to nonsignificant results are

discussed.

ACKNOWLEDGMENTS

I wish to thank the four members of my committee, Drs. Hiram Fitzgerald,
Mark Rilling, Ellen Strommen, and Lauren Harris for their help and
support throughout this endeavor. I especially wish to thank my advis-
or, Dr. Fitzgerald, whose kind and valuable advice has added immeasur-

ably to my personal and academic growth.

ii

II.

III.

IV.

VI.

VII.

VIII.

IX.

XI.

XII.

XIII.

TABLE OF CONTENTS

LIST OF TABLES
LIST OF FIGURES
INTRODUCTION
LITERATURE REVIEW
RESEARCH QUESTIONS
METHOD

PROCEDURE

RESULTS

DISCUSSION
APPENDIX A
APPENDIX B: TABLES
APPENDIX C: FIGURES

LIST OF REFERENCES

iii

13

15

18

22

25

33

37

53

59

Table 1.

Table 2.
Table 3.
Table 4.

Table 5.

Table 6.

Table 7.

Table 8.

Table 9.

Table 10.

Table 11 .

Table12.

Tab1e13.

Table 14 .

Table 15.

Analysis of

Analysis of
Analysis of
Analysis of

Analysis of
Variability

Analysis of
Variability

Analysis of

Analysis of
Variability

Analysis of
Differences

Analysis of
Differences

Analysis of
Variability
Slide

Analysis of
Variability

Analysis of
Differences

Analysis of
Variability

LIST OF TABLES

Variance Summary
Table to Blank Slide

Variance Summary Table to Baby Slide

Variance Summary Table to Baby Sound

Variance Summary Table to 250 Hz Tone

Variance Summary Table for Heart Rate

to Blank Slide

Variance Summary Table for Heart Rate

Variance Summary Table to Baby Sound

Variance Summary Table for Heart Rate

to 250 Hz Tone

Variance Summary Table for Heart Rate
to Checkerboard and Blank

Variance Summary Table for Heart Rate
to Baby Sound and Tone

Variance Summary Table for Heart Rate

Differences to

Checkerboard and Blank

Variance Summary Table for Heart Rate

Differences to

Baby Sound and 250 Hz Tone

Variance Summary Table for Heart Rate

to Baby Slides

Variance Summary Table for Heart Rate

Differences to

Baby Slides

Menu-Whitney U Test for Differences in Initial
Variability by Bayley Group

iv

39

4O

41

42

43

44

45

46

47

48

49

50

51

52

Figure 1.
Figure 2.
Figure 3.

Figure 4.
Figure 5.

LIST OF FIGURES

Heart rate change to the auditory stimuli.
Variability change to blank slide presentation.

Heart rate change to the checkerboard and blank stimu-
11.

Heart rate change to the two baby slides.

Variability change to the 250 Hz tone divided by
Bayley group.

56

57

58

Introduction

Infant Attention

 

Recent methodological and technical advances in the study of infant
attention (see Salapatek, 1975; Cohen & Gelber, 1975; Lewis, 1974 for
reviews) have renewed interest in a field long hampered by inadequate
and unquantifiable response measurement. These advances have allowed
responses long noted by infant observers (i.e., Darwin, 1877) to be used
in experimental paradigms directed toward an analysis of the processes
which underlie cognitive development during infancy and early childhood.

In this expanding body of literature, the matter of defining atten—
tion acquires significance since the term has been used in a variety of
contexts (c.f., Bakan, 1966; Lewis, 1971; McCall, 1970). Essentially,
definitions of infant attention can be categorized into two rough clas-
sifications. The first definition uses an overt measure of attention on
the strength of its apparent face validity. Examples of this approach
are the use of looking time in habituation and paired comparison pro-
cedures to study recognition and memory (Fagan, 1977; Cohen & Gelber,
1975; Lewis, 1971). To be sure, in these and similar studies attention
often is viewed as a necessary process. However, in many instances the
specific question being scrutinized concerns the development of certain
cognitive operations (Lewis, 1974) rather than the attentional process
itself.

In contrast, the second definition of attention views it as a
specific, albeit global, system.that can be examined separately from
other aspects of cognitive development. This latter viewpoint is char-
acteristic of adult cognitive models (Kahneman, 1973), neurological
models (Routtenberg, 1968), and syntheses of these two approaches

1

(Sokolov, 1963). Psychophysiological studies of attentional mechanisms
in adults (Maltzman & Raskin, 1965; Zeiner & Schell, 1971), and in
infants (see Graham & Jackson, 1970; Clifton, 1974 for reviews) are
prominent examples of the latter approach. In many studies with infants,
a cardiac measure is the primary psychophysiological dependent variable
used to infer attention. This is due to the ease of measuring the
cardiac response, the attachment of psychological significance to the
directionality of the response (acceleration vs. deceleration) (Graham

& Jackson, 1970), and the questionable reliability of commonly used
adult measures (e.g., skin conductance; see Porges, 1974).

The foundation and relevance for the study of attention from a
psychophysiological perspective is derived from the hypothesized
importance of attentional mechanisms for cognitive development (Jeffrey,
1968; Furby, 1974). In its most molecular form, attention to the condi-
tional stimulus is a necessary aspect of conditioning if a contingency
between two environmental events is to be recognized. In studies using
a two choice discrimination task with mentally retarded subjects, Zeaman
and House (1963) plotted backward learning curves which appear to indi-
cate that learning occurs rapidly once attention to a stimulus is estab-
lished. A similar explanation has been mentioned by Gelber and Cohen
(1975) to describe the backward learning curves they obtained in their
studies of infant habituation, although these studies are more tenta-
tive. The rationale of a causal relationship between attentional pro-
cesses and cognitive development underlies much of the extant research
concerning attentional processes in infants. Although the exact mech-
anisms by which cognition and attention interact are still largely

unknown, researchers have assumed and adopted a relationship between

 

these two processes to study both the cognitive capabilities of infants
and strategies which maximize or minimize attentional response (Clifton,
1974; Graham & Jackson, 1970; Kagan & Rosman, 1964; McCall, 1970;
Sameroff, 1971, 1972).

The present study attempted to investigate two aspects of the rela-
tionship between cardiac and behavioral responses of attention during
infancy. The first question of interest concerned the concordance of
cardiac and behavioral measures of attending, whether this relationship
would discriminate between stimuli of different content. Previous
investigators have examined this question by linking the reflexive
cardiac OR to behavioral measures but have not attempted to link the
sustained cardiac attentional response to behavioral indices of atten-
tion.

The second question of interest involved the relationship between
cardiac attentional responses and measures of the infant's develop-
mental status. Limited support for the existence of relationship between
attention and development is derived from a small number of studies.
However, to validly establish individual differences in cardiac atten-
tional responsivity during infancy, the reliability of the measure
under examination must be established. To achieve this prerequisite
to the study of individual differences, the present study used two
trials of very similar stimuli to establish intrasession reliability.

As will be described, a variety of factors can dramatically affect

these responses, and reliability is a necessary condition before analyz-
ing the relationship between psychophysiological responses and other
developmental measures.

The differentiation of individuals on the basis of attentional

responsitivity is a direct conceptual application that presents many
methodological difficulties. The first problem, previously mentioned,
is obtaining adequate and reliable dependent measures of infant atten-
tion. No less important for a study of this type is defining an ade-
quate criterion measure to serve as an indicator of developmental
status. For the latter difficulty, the Mental Development Scale, from
the Bayley Scales of Infant Development (Bayley, 1969) was administered
to each infant. For cardiac measures, a two component model was chosen
to interpret attentional responses, and is described below. A descrip-

tion of the Bayley Scales is given later.

Literature Review

Psychophysiological Correlates of Infant Attention

In the Principles of Psychology, James (1962) constructed a three
factor description of attention, where attention consisted of a focus
(sensoral vs. associational), a rationale (immediate vs. associational),
and a method (involuntary vs. active). Porges (1974) has identified
two psychophysiological responses which are postulated to parallel a
phasic, immediate response to stimulation and a tonic sustained response
(analogous to James' involuntary and active responses, respectively).

Porges' model reflects the recent synthesis of two separate psycho-
physiological lines of research. The first is reflected both by the
work of Sokolov and Lacey; the second primarily by the work of Porges.
Each is discussed in turn.

Sokolov's Mbdel. The study of reactive component of attention has
a far longer history than the study of tonic response and, until
recently, has been synonymous with attention in infant research, this
despite the recognition of the active dimension cited by James for
which the reactive component alone cannot account (Lynn, 1966). The
reactive component can be identified as the "orienting-investigatory"
or "What-is it?" reflex first described by Pavlov in 1927.

As another example of a reflex which is very much neglected

we may refer to what may be called the investigatory reflex.

I call it the 'What is it?‘ reflex. It is this reflex which

brings about the immediate response in man and animals to

the slightest changes in the world around them, so that they

immediately orientate their appropriate receptor organ in

accordance with the perceptible quality in the agent bring-

ing about the changes, making full investigation of it.

(Pavlov, 1927, cited by Lynn, 1966)

Sokolov (1960, 1963) systematically reviewed both the literature

and empirical research on the orienting reflex (0R), concluding with a

5

activation of the EEG, i.e., desychronization. (Lynn, 1966)

Elicitation of the OR or defensive reflex is not simply a function
of qualitatively different stimuli: variations in the parameters that
describe the physical characteristics and properties of a stimulus can
alternatively lead to rejection or orientation to a stimulus (Graham,

& Jackson, 1970; Lynn, 1966). Orientation reactions, similar to other
behaviors, can become both conditioned (when the stimulus acquires sig-
nal value) or habituated (Floru, 1975).

The Laceys' Model. The Laceys' (Lacey, 1959, 1967; Lacey & Lacey,
1974) have developed a model of attention similar to that proposed by
Sokolov which recognizes autonomic parallels to "stimulus intake" and
"stimulus rejection" (specifically heart rate deceleration and heart
rate acceleration, respectively). The autonomic response is moderated
by situational stereotypy; that is by the set of environmental conditions
interacting with the individual's history to produce the autonomic
response. The Laceys' view the autonomic response as part of a feed-
back mechanism wherein the cardiac response facilitates the cognitive
reaction (note the parallel to James' theory of emotion). Both aspects
of the Lacey model (the response and its hypothesized mechanisms) have
been criticized (see Elliot, 1974; Obrist, Webb, Sutterer, and Howard,
1970), but a number of these criticisms are inapplicable to infant sub-
jects, as will be noted later.

Graham and Clifton (1966) synthesized the work of Sokolov and Lacey
into a framework that equated stimulus intake with an orientation reac-
tion and stimulus rejection with the defensive reaction. Nonhuman,
human, adult, and infant studies were reviewed in order to support their

interpretation. A more recent elaboration (Graham & Jackson, 1970)

7

cites an expanded base of research support for the previous position,
while also noting the potential for studying cognitive development
through the use of psychophysiological dependent measures.

In context of the Graham & Jackson hypothesis, the occurrence of
a decelerative shift in early infancy is postulated to be of psycholog-
ical significance. The decelerative shift is a well documented change
in the ease of eliciting a decelerative response to a non-signal stimr
ulus over the first six months of life. During the newborn period,
responses to non-signal stimuli are predominantly accelerative (although
recently a number of experimenters, i.e., Adkinson & Berg, 1976; Lipsitt
& Jacklin, 1971; Kearsley, 1973; Parmeleau-Malcuit & Clifton, 1973, have
elicited deceleratory responses by careful choice of stimuli and con-
trol for identified possible confoundations, e.g., state, prandial lev-
el). By six months of age, cardiac responses change to deceleration
for the same stimuli that had previously elicited acceleration (Clifton
& Meyers, 1969; Lipton, Steinschneider and Richmond, 1966).

Graham and Jackson emphasize strongly the possibility of this shift
being indicative of a distinct change in the infant's interaction with
the environment. A derivative view (Samaroff, 1971) accounts for poor
conditionability in early infancy as a consequence of the inability to
exhibit cardiac orienting reactions (although other authors, i.e.,
Fitzgerald & Brackbill, 1976, have disputed this view). In either case,
much evidence indicates major psychological shifts in behavior during
this period. Lewis (1971) has cited data from.studies of visual respond-
ing to redundant stimuli, the loss of primitive reflexes, and changes
in the EEG component waveforms to underscore change over this time. A

recent review (Emde & Robinson, 1976) further documents behavioral and

8
neurobiological shifts during the first trimester of life.

Porges' Model. The study of psychophysiological parallel of the
tonic component of attention has a more recent history, and is due prim-
arily to the work of Porges and colleagues (Porges, 1972, 1973, 1974,
1977, 1978; Porges, Arnold & Forbes, 1975), although this factor had
been noted previously (Lacey, 1967). Porges' two component model of
heart rate response (Porges, 1974) is a psychophysiological model whose
concomitants are empirically testable as cardiac responses. The phasic
component can be identified as the 0R discussed above whereas the active
component is manifested as a reduction in heart rate variability. Heart
rate variability responses are also quantifiable and testable in a par—
adigm examining individual differences. Porges (1974) has reported dif-
ferences in newborns classified on the basis of their spontaneous heart
rate responses, where high variability newborns were found to respond
differently from low variability newborns to the offset of an auditory
stimulus. Recent work with hyperactive children also indicates the
applicability of heart rate correlates of attention for studying atten-
tional processes (Porges, 1977), and further supports this model.

Van Hover (1974) has added support for the model by reporting a study
validating the existence of these two separate components of attention
in an older sample of children.

The use of tonic measures of attention to distinguish among stimuli
to which infants show equivalent amounts of overt attention (or looking
time) appears to be virtually non-existent in the literature. Recent
reports using a measure of coherence (the relationship between respir-
ation and heart rate, Porges, 1978) appears to be a sensitive method of

assessing this component. Many previous studies have demonstrated

redefinition of the 0R that was more limited and restricted but one

that, because it is specifically defined in terms of certain behavior-

al and autonomic responses, is empirically testable. Included as
responses indicative of orienting were electroencephalographic changes,
electrodermal activity, and certain vascular changes. However, it was
evident from the work of Sokolov and others (e.g., Floru, 1975) that the
0R could not lead to the far reaching consequences hypothesized by Pavlov
for human development (c.f., Lynn, 1966). This is apparent in the fol-
lowing passage from Sokolov (1963):

By orienting-investigatory reflex, we mean the series of
reactions bringing the animal into contact with the object
and tuning the analyzers of the animal or man, so that per-
ception of the stimulus takes place in the most favorable
conditions. This definition of the orienting-investigatory
reflex is, however, too wide. The orientation reflex in
the restricted sense of the world should be distinguished
in the reflex as the non-specific reaction resulting in the
tuning of the analyzer when exposed to a new stimulus. This
elementary reaction is quite distinct from the complex
exploratory chain of reflexes, aiming at investigation of
the object in detail and involving a whole series of condi-
tioned orientation reflexes.

In this book, the orientation reflex is analyzed in the
restricted sense. (Sokolov, 1963)

Sokolov further describes a defensive reflex which serves to psych-
ologically detach the individual from contact with an aversive stimulus.
In contrast, the OR is hypothesized to facilitate learning by height-
ening subject response and sensory intake to an environmental event.
Lynn (1966) has described the orientation reaction components as fol-
lows:

Orientation has been indexed by a quieting of general behav—

ior which permits the organism to attend to the environment.

Typically the reaction has involved slowing of heart rate

and respiration and cessation of gross activity. In addi-

tion, there is activation of perceptual systems, i.e., turn-
ing of sense organs towards the source of stimulation, and

10

phasic differences to stimuli (see Clifton, 1974), but these are prim-
arily between stimuli of high and low signal value.
Previous Research

The application of psychophysiological techniques to differentiate
between individuals in their rate of learning is restricted to only a
few studies. All used a psychophysiological response as a measure of
attention, and each related the magnitude of this measure (or groups
formed on the basis of this response, i.e., high-low) to a performance
measure. Using the narrow Sokolovian definition of orienting, Ingram
and Fitzgerald (1974) reported a significant relationship between learn-
ing a conditional discrimination and the magnitude of the orienting
reflex (defined as the skin potential response to an auditory stimulus)
in 3-month-old infants. Ingram (1973) also found a similar effect in
3% month old infants where subjects with higher 0R magnitudes (also
defined by the skin potential response) exhibited more rapid learning
during the conditioning of differential eyeblink responses. Nelson
(1974), using a similar procedure, obtained virtually identical results
with Down's Syndrome and mixed-etiology subjects (i C.A. - 11 years,

11 months; le.A. - 1 yr., 5 months). In the Nelson study, significant-
ly, the OR was determined by measurement of the cardiac responses of the
subjects to an auditory stimulus.

More recently, Cousins (1976) has extended the Ingram & Fitzgerald
finding to grade school children (9-11 years of age), also using a card-
iac measure of orienting, and a conditioned discrimination paradigm.
After a systematic review of the literature only these four studies
appear to examine the question of the relationship between individual

difference in psychophysiological measures of attention and learning

11

in infants and children. An older related study (Kagan & Rosman, 1964)
reported greater deceleration for let and 2nd grade boys who exhibited

"non-analytic"

an "analytic" attitude as opposed to those who showed a
cognitive mode; but unfortunately, this study only compared group effects
and used questionable methods of computing the cardiac deceleration.

In addition to these few findings, a separate line of inquiry has'
examined the difference in the orienting responses between normal and
retarded subjects. The majority of these studies are tests of Luria's
(1963) suggestion that retardates should show a weaker 0R than normals,
and that this response habituates more rapidly in this population. A
number of these studies (e.g., Powazek & Johnson, 1973) have found lit-
tle support for Luria's suggestion, in fact finding no heart rate
response difference between the two groups.

A more recent study (Porges & Humphrey, 1976) examined this same
question from the two component model rather than from an analysis
of heart rate alone. Using an approximate Mental Age matched design,
Porges and Humphrey showed a decrease in the heart rate variability
for the normal subjects during a task requiring sustained attention, and
an increase in the variability for the retarded subjects during the same
period. Although this study examined only gross group differences, the
result further supports use of the two component model for examining
individual differences.

The dearth of studies examining the relationship between psycho-
physiological measures and performance reflects the recent development
of infant psychophysiology as a discipline. Despite this, theoretical
and practical considerations signify the use of 2-4 month old subjects

for a more powerful test of the possible influence of attentional

12

mechanisms. Newborn studies (i.e., Porges, 1974) are confounded by
such factors as infant birth trauma and the effects of any labor medi-
cation which may depress infant responsitivity (Adkinson & Berg, 1976;
Stechler, 1964; Freidman, Brackbill, Caron, and Caron, 1978). Reli-
ability from the newborn period to the 3rd month is low (Lipton,
Steinschneider, & Richmond, 1966; Clifton & Graham, 1968) owing possi-
bly to the factors described above in addition to both the decelerative
shift and the rapid maturation of the infant. In context of this and
the results of the previous discussion, there appears to be a need for
an evaluation of whether cardiac responses do have any developmental
significance.

From the preceding literature review, it can be inferred that card-
iac orienting is possibly a significant developmental variable. The
goal of the method that will be described was to test whether a rela-
tionship could be found between measures of orienting and development-
al level in early infancy. A specific difference between this and
prior studies was to look at the global development of the infant rather
than at a narrow criterion of infant performance, e.g., habituation.

It was felt that if orienting or attentional vigilance was an important
early variable, there should be differences between relatively advanced
infants and less advanced infants on this dimension.

The instrument I chose to evaluate developmental status during
infancy was the Mental Scale of the Bayley Scales of Infant Development
(Bayley, 1969). These scales have a long history, being originally
developed for the Berkeley Growth Study during the 1930's and recently
restandardized. There are three separate scales in the instrument: a

mental scale, a motor scale, and an infant behavior record. Neither the

13

motor scalerunrthe behavior record were administered, the former due to
the small number of items present in early infancy, the latter because
it has yet to be standardized.

The mental scale does have a relatively large pool of items, the
exact number dependent on the level at which administration begins (in
any case, the maximum number of items is 45 at four months). The mental
scale is well standardized, and is highly reliable over short periods of
time, even at three months of age (McCall, et al., 1972; Thomas, 1970).
An additional reason for using the Bayley was a prior factor analysis
of the mental scale content (Stott & Ball, 1965) which reported atten-
tional factors present in the majority of the items analyzed.

The primary goal of the present study was to examine the relation-
ship described above. As mentioned before, however, a number of addi-
tional questions could be examined to test the usefulness of cardiac
measures as an index of infant attention. These questions were designed
to assess whether the cardiac measures could differentiate between dif-
ferent stimuli to which the infants either showed or didn't show attend-
ing behavior (indexed by monitoring their looking behavior during visual
stimulus presentation). This analysis is also unique by the application
of a tonic measure of orienting.

Research Questions

The method to be described was used to allow examination of the fol-
lowing questions:

1) Can the two component model of heart rate response be used to
differentiate between stimuli with unequal behavioral measures of atten-
tion? Previous work validating the two component model (Porges, 1974)

has been restricted to the use of simple, nonsignal stimuli without the

14

use of a behavioral referent. Many previous investigators have cited
the lack of a sensitive measure to establish individual differences
in infant behaviors (e.g., Horowitz, 1974). It was hoped that the pres-
ent study would yield progress toward the use of a more sensitive card-
iac measure to discriminate between stimuli. If a distinction between
two stimuli of greatly varying signal value (discussed later) could be
realized, then a second test would be performed to see if cardiac mea-
sures could discriminate stimuli to which infants reactions are behav-
iorally equivalent. The main assumption for this question was that
infants would show a relatively larger tonic reaction to signal or
"salient" stimuli in these modalities with less attractive properties.

2) Are both the reactive and tonic components of the cardiac
response reliable, i.e., are the heart rate functions similar to sim-
ilar stimuli during the short term laboratory session? A prior study
of the orienting response (specifically the phasic component) in a
longitudinal study of infants from 2% to 5 months of age (Lipton,
Steinschneider, & Richmond, 1966) has indicated significant consist-
ency of this response, but the stimulus chosen (a mild air stream to
the abdomen) yielded a heart rate acceleration. In addition, the same
study yielded a significant correlation for prestimulus heart rate
(r 8 .62), and for certain measures of response magnitude. However,
poor stimulus choice and possible misinterpretation of the response
weakens this result. No other studies have examined the question of
the reliability of the phasic heart rate orienting response.

3) Are psychophysiological responses correlated with the results
of the Mental Development Index from the Bayley Scales of Infant Develop-

ment? The preceding literature suggests that there should be a

15

relationship between the cardiac concomitants of orienting and scores
on the Bayley Scale. Other authors (e.g., Crano, 1977) have hypothe-
sized that the primary determinant of infant behavior on exams similar
to the Bayley Scale is the biological maturation of the infant rather
than a stable cognitive characteristic. The rationale for use of the
Bayley has been described above; use of both signal and nonsignal stimr
uli will enable the test of whether an interaction exists between the
reaction to a given stimulus type and the level of relative development-
al precocity as indexed by the Bayley.

The procedure was therefore designed to explore these questions
by exposing the infants to two different stimuli in both the auditory
and visual modalities. One of each pair was chosen as a stimulus to
which the infants would show prolonged looking behavior and hopefully
a simultaneous tonic attentional response. After this, the Bayley
Mental Development Scale was administered to see if the ability to show
a prolonged tonic response was related to relative developmental status
in the group tested. Two additional visual stimuli were used to see if
the infant response was reliable over the short term laboratory session.

Method

Subjects

Subjects were full term, clinically normal infants ranging from 85
to 127 days at time of testing. Babies were solicited by a direct mail-
ing to mothers whose names were obtained from the birth records of
Ingham County, Michigan, and whose addresses were then taken from the
most recent telephone book. Although an effort was made to recruit as
many subjects as possible, the final sample analyzed consisted of 2 males

and 10 females, from a total of 77 sessions in the laboratory. The

16

primary factor contributing to subject loss was the failure of the major-
ity of infants to complete the experimental session.

All parents were asked to sign a release form before any testing
was done (see Appendix A). Information to insure that the baby was
full term and had no developmental difficulties was obtained by parent
interview and by asking the parent to fill out a brief questionnaire on
the child's history (Appendix A). The original intent was to obtain
the subjects as close to ninety days as possible, but unfortunately, this
was difficult to achieve in practice. The final mean age was 101 days,
with 92% between 90 and 120 days of age at the time of final testing.
Apparatus and Stimuli

Cardiac responses were monitored on a Grass Model 7 Polygraph, with
output recorded on both scaled paper and a Vetter FM tape recorder
(1 7/8 ips). Three Beckman Ag/AgCl biopotential miniature electrodes
were attached to the infant's chest to serve as direct input to the poly-
graph. The inside of each electrode was filled with Beckman Electrode
paste to increase conductivity. Active electrode placements were sym-
metrical above the infant's nipples, with a third ground electrode
placed 1/4 inch above the navel.

Stimuli were chosen to test each of the previously mentioned ques-
tions. Visual stimuli were:

a) a blank slide which served as an illumination change to the
infant

b) two slide photographs of young infants (approximately three
months of age, one male and one female)

c) a 15 square by 15 square black and red checkerboard, each unit

appearing as an approximately 1.75 cm square when projected.

17

Each of these stimuli was presented by a Kodak Carousel Model 500
slide projector onto a rear projection screen in the booth where the
infant was located. The size of the two infant slides when projected
was 21 cm by 31.5 cm on the screen. The blank slide filled approxi-
mately a 31.5 cm by 31.5 cm area, although this was diffuse rather than
concentrated. The checkerboard was on a blue background with the red
and black squares in the center of the slide; the entire slide was 21
cm by 31.5 cm. White noise was continually present during the experi-
mental session to mask the sound of the projector changing. Between
slide presentations a black slide to mask all light was used.

Two auditory stimuli were also presented:

a) a 250 Hz sine wave, with a .5 second rise time

b) a recording of an infant cooing (approximately four months of
age)

These stimuli were recorded and then played back on a Wollensak
casette deck which was connected to an 8 ohm impedence speaker in the
infant chamber. Playback in the chamber was at 75 db; ambient level
was 65 db due to the white noise.

The stimuli were chosen across two dimensions of modality and
salience in order to test the questions described earlier. The check-
erboard was chosen as a stimulus that has previously been shown to elicit
both behavioral (e.g., looking preference) and physiological orienting
at a number of infant ages (Fantz, 1964; Kagan, 1972); the cooing sound
was similarly chosen as a stimulus that contained signal properties. It
was hoped that these stimuli would show both tonic and phasic differ-
ences in orienting when compared with the nonsalient stimuli (the light

and the tone), although the test of primary interest involved the tonic

l8

measure. An extension of the two component model would predict that
there would be a continued response to these stimuli and none to the
light or tone. Thus two dimensions of salience were defined in each of
the two modalities (auditory and visual) of stimulus presentation to
answer question 1. The baby slides were used to check reliability of
the infant responses (question 2 above), and also to be used as a sec-
ond salient stimulus if a comparison of the checkerboard and light
proved significant. In this case a test of the baby versus checkerboard
would be made to check if two salient stimuli could be distinguisehd.
They were also used to examine the relationship between the Bayley Men-
tal Scale score and cardiac responsivity, as were the two nonsalient
stimuli (question 3 above). It should be noted that what I have defined
as the salience of different stimuli could be considered synonomous
with the characteristics of the checkerboard (i.e., contrast; Fantz,
1970) or coo (possibly spectral complexity; Clarkson & Berg, 1978) which
elicit a behavioral reaction in addition to the physiological monitor-
ing. For the visual stimuli in this study, salience was defined as the
difference in looking time towards the screen. There does not appear to
be an analogous measure for the auditory stimulus.
Procedure

All testing was done at the Developmental Psychobiology laboratory
located in the Psychology Research Building, Michigan State University.
Testing for the Bayley Scale was done in another room of the same build-
ing, where appropriate furniture and a crib were provided for both par-
ental comfort and administration of the Bayley Scales.

Upon arrival at the laboratory the parents (and/or guardians) were

19

greeted by the experimenter and assistant. Parents were again explained
the purpose and design of the study previously described in the mailing.
After a brief tour of the laboratory, the parents were asked to sign
the permission slip and to fill out the developmental questionnaire.
They were also asked to fill out an address form so they could receive
the results of the study, and thanked by the experimenter for partici-
pating in the study.

The child was then taken into the psychobiology laboratory where
the experimenter or assistant undressed the child as much as necessary
for the electrodes to be attached. The areas for electrode placement
were lightly cleaned with an alcohol pad (70% ethanol) and the elec-
trodes then attached. The parents were then asked to carry the infant
into the research booth where the slides were presented, although in
some cases it was necessary to use the infant's car seat rather than the
laboratory seat to keep the child more comfortable.

The mother was seated behind the infant, and asked not to inter-
fere with the infant's behavior in any way during the session, barring
obvious infant discomfort, of course. For a minute or so the mother was
engaged in conversation to acclimate both herself and the child to the
experimental environment. -(It should be noted that a large number of the
infants were quite reluctant to accept not having the mother in visual
contact.) The mother was asked not to communicate in any way with the
infant, and also asked not to use any form of pacification.

If the child was sufficiently calm, the experimental procedure was
started. The experimenter stayed in the equipment room of the labora-
tory where the polygraph was located and the presentation of stimuli was

controlled. An assistant to the experimenter stayed where he or she was

20

able to monitor both the looking preference and state of the infant,
this being done through a peephole below the center of the rear pro-
jection screen on the outside wall of the booth. The assistant was
instructed to press two buttons, one to signify if the infant was look-
ing or not looking towards the screen, the other to indicate to the
experimenter that the infant was in a less than optimal state for con-
tinuing (assessment of infant state was based on the five level scale
proposed by Brackbill and Fitzgerald [1969], where the acceptable states
were either state 4 or 5, quiet or active awake). In addition, the
experimenter in the equipment room could monitor a microphone that was
in the experimental booth. During the session, if the infant wasn't in
either of the acceptable awake states, the procedure was halted and
appropriate decisions made on whether to continue.

The experimenter monitored both the polygraph and tape deck, in
addition to controlling the stimulus presentations. Visual stimuli were
presented for a minimum.of 25 seconds, auditory stimuli for a minimum of
15 seconds with times calculated by using the polygraph timing mark.
There was a variable intertrial interval of 30 to 40 seconds C; I 35
seconds) to allow the infant's heart rate to return to baseline. Four
different stimulus presentation orders were used, with the only require-
ment that the two infant slides always were in the same relative order.
The male slide was presented after the female slide, regardless of its
place in the order of stimuli.

After the session was completed, the electrodes were removed from
the infant. Parents were now asked to carry the infant back to the crib
room where the Bayley Mental Development Scale was administered. After

this parents were invited to examine the polygraph record and to ask any

21

questions regarding the procedure. In no case, however, was any com-
parison between the present subject and previous subjects made to the
parent.

Twenty parents were invited to the laboratory prior to the first
physiological session for the experimenter to gain facility with both
the Bayley and the handling of young infants in general. Learning of
the Bayley was aided by the advice given by Dr. Thomas Taflan-Barrett
of the Ingham County Community Mental Health Center, although in the
author's opinion it was only after a good deal of practice that admin-
istration of the scales was considered to be accurate. (It should be
noted that only the very first part of the scales needed to be used for
this study--1earning of the entire range of Bayley items would be a far
more formidible task.) Similarly, the first six physiological sessions
were disregarded, as they were used primarily to establish reliability
in the assistants' monitoring of the infant eye movements. This was
done by having two assistants at a time monitor the same infants and
push two separate buttons, which afterwards were compared for similar-
ity. A quantitative measure was never computed since the records were
quite similar visually. Three additional sessions were disregarded dur-
ing the course of the experiment due to experimenter error or equipment
failure.

After the sessions were completed, the tapes were subsequently
played back through the polygraph to get a final copy of the record.

The polygraph was run at 50mm/sec for this record, and a Krohn-Hite Mod-
el II filter was used to reduce any noise present on the tape recording.
These cardiac records were then hand scored by the experimenter and an

assistant for the interbeat intervals (1313), the time between each

22

Rewave peak in the cardiac cycle (these were subsequently checked for
reliability by the experimenter, r-.97). The IBIs were converted into
a weighted average of heart rate in beats per minute for the five sec-
onds prior to each stimulus through the five seconds after the stimulus
by a program written for a Hewlett-Packard 2000 computer. A weighted
average accounts for all the partial beats that fall in a one second
interval by adding the proportion of each beat that falls in the inter-
val, and then converting the average of all beat and partial beats from
the interbeat interval measure of milliseconds to beats per minute. The
analyses that will be reported in the results section are calculated
using the beats per minute measure for each second of response time.
Variability was scored for five second blocks from the five seconds pre-
stimulus to the five seconds post stimulus. Each variability period was
the variance of the five beats per minute values for that five second
block.
Results

Separate analyses of variance were computed with heart rate as the
dependent variable to test each of the previously mentioned questions.
To accomplish this, a separate analysis was done for both the absolute
changes in heart rate and the variability changes in the same measure.
Absolute heart rate change was obtained by subtracting the rate for the
last second prestimulus from the rate for each second of the stimulus
period. The variability measure was the rate variance for the five sec-
ond prestimulus period, each five second block during stimulus presen-
tation, and for the five second post stimulus period. The alpha level
for each test was set at p-.10. This was done in consideration of many

methodological problems that most likely inflated the error variance, and

23

will be described later. All analyses of variance results are summa-
rized in Appendix B.

Tests for discrimination between salient and nonsalient stimuli.

To test whether infants could discriminate on this dimension, four sep-
arate analyses were done. The first two compared the blank slide.and
checkerboard (for absolute change and variability period change), the
latter two similarly comparing the tone and coo. Each of these tests
was a completely crossed repeated measure Anova (AxBxS; Keppel, 1973).
where the subjects' factor was crossed by stimulus and either seconds
(for rate) or period (for variability).

Discrimination of tone versus coo. For the absolute rate analysis,
there was evidence of a significant difference in cardiac response to
the tone and the baby sound (F(1,11)=4.14, p <.07). The main effect for
seconds was nonsignificant (p>’.10), as was the interaction for stim-
ulus by time (this effect is illustrated in Figure 1). The variability
analyses for the same stimuli yielded nonsignificant F-ratios for each
of the main effects and a nonsignificant interaction for each (all p's
> .10).

Discrimination of blank versus checkerboard. In the rate analysis,
there were nonsignificant effects for the stimulus differences and
interaction, although there was a strong main effect for time (F(24, 264)
32.19, p <.002; see Figure 3). The variability analysis was similar to
the comparison of auditory stimuli, with both main effects and inter-
actions yielding nonsignificant F values (excepting a main effect for
period for the response to the blank slide (F(6, 60)=l.91, p <.10); see

Figure 2).

Reliability of Infant Slide Response

 

An analysis similar to the previous one, using the two infant
slides as the independent variable yielded nonsignificant effects for
the two slides and interaction, although there was a strong main effect
for seconds (F(24, 264)=1.95, p <.006, graphed by separate slides in
Figure 4). This was taken as evidence that the infants strongly ori-
ented to both of the slides when the nonsignificant interaction is con-
sidered. The variability analysis yielded nonsignificant ratios for
each test. Although more properly a generalizability coefficient should
be computed (Cronbach, Gleser, Nanda, and Rajoratnam, 1972) rather than
a simple ANOVA, it was felt that in consideration of the methodological
problems to be described any computation of reliability would be mis-
leading. This analysis will therefore be deemphasized, and the relia-
bility of responses tentatively assumed.

Tests for the Relationship Between Bayley Scale Scores and Cardiac
Responses

To test whether there was any relationship between the Bayley MDI
Scale scores and the infant responses; the Bayley scores were first medi-
an split into high and low scale groups (the high group mean was 111,
range 100-130; the low group mean was 93, range 85-96). This factor was
then used in a mixed design repeated measures Anova (Keppel, 1973),
where subjects were nested by group and then crossed with time [Ax(BxS)].
Although this factor could have been included by converting the prior
analysis to the prOper mixed design, computer considerations led the
author to perform the analyses separately. The stimulus trials used for
analysis were the first infant and blank slides for visual stimuli, and

the coo and tone auditory stimuli (the choice of the infant slide was

24

25

arbitrary; both the infant slide and checkerboard were looked at for
equivalent periods). A total of eight Anovas were therefore performed,
four on the absolute rate and a similar four on the variability.

For each of these analyses, none of the interactions of group by time
were significant, and thus these effects can be ignored. Tests for
the main effect by Bayley group were also all nonsignificant, except for
the analysis of the variability response to the tone (F(l,10)=5.926,P“-04
see Figure 5). A separate Mann-Whitney U test on the 25 seconds of
baseline recording prior to the first trial was also nonsignificant for
the Bayley median split.

The pattern of results thus strongly supports evidence of visual
orienting as indicated by the prolonged deceleration to these stimuli.
The pattern of looking during stimulus presentation showed prolonged
looking only to the checkerboard and infant slide. Only one infant
looked towards the screen less than 752 of the presentation time. Sim-
ilarly, only one subject (a different infant) looked towards the screen
more than 252 of the time the other stimuli were presented. Interpre-
tation of the cardiac orienting effects and the nonsignificant effects
by Bayley group are discussed below.

Discussion

 

The primary purpose of the present study was to determine whether
individual differences in cardiac responsivity were related to individ-
ual differences in developmental level. The results of the analysis to
answer this question were negative, despite yielding what appears to be
strong evidence of cardiac and behavioral orienting in early infancy.

As will be discussed below, however, problems during the data collection

would have tended to mask differences between the Bayley groups if they

26

were present.

The results of the three analyses that compared two different stim-
uli for function differences (blank versus checkerboard, tone versus coo,
and the comparison of two infant slides) indicated definite orienting
responses to the visual pairs. This response, a rapid initial acceler-
ation, prolonged deceleration, and return to baseline is similar to the
response elicited by many previous studies of orienting (e.g., Berg,
1974) and the predicted response to nonaversive stimuli described by
Graham and Jackson (1970). The differential response by the infants to
the auditory pair is particularly interesting when interpreted by the
Graham and Jackson model. During the playback of the tone, variation in
the cassette recorder motor speed created a noticeable warble (unfor-
tunately, no other equipment was available). Assuming that the tone was
relatively noxious to the infant, the rapid return to baseline and accel-
eration to the tone could possibly reflect what Graham and Jackson inter-
pret as analogous to a Sokolovian defensive reaction (relative to the
prolonged orienting when the coo was presented).

As described in the introduction, previous studies have found def-
inite signs of orienting in three-month-old infants; the present study
replicates and'supports these findings. Unfortunately, there were no
significant differences between the blank and checkerboard, nor any sig-
nificant discrimination when the subjects were separated by Bayley
scores. Although the non-significant effects are possibly due to the
true lack of main effects, the methodological difficulties in the study
were such that any subtle effects were likely to be hidden by inflated
mean square error terms (see Appendix B). These difficulties are dis-

cussed below.

27

Methodological problems. The problem of greatest concern in this
regard was the poor reproducibility and scoring of the actual heart rate
data. The EKG waveforms, as previously mentioned, were analyzed by play-
ing back the recorded tape through a filter into the polygraph, operating
at 50mm/sec. These resulting wave forms were then hand scored with a
millimeter ruler by the experimenter. Even though the scoring was
checked to establish reliability, the combined error from three sources
(the tape deck, the drive motor of the polygraph, and the hand scoring)
seems more than large enough to mask subtle main effects between either
the visual stimuli or the two Bayley groups (as an estimate of the pos-
sible error magnitude, a 1cm error in scoring is translateable to
approximately a 3 beat per minute difference after transformation).

When originally designing the procedure and method for this study, the
experimenter assumed the use of a LINC-8 computer to score the heart
rate tapes and yield a relatively errorless digitized record. Mechan-
ical difficulties precluded using this piece of equipment, and thus hand
scoring was necessary.

This difficulty was intertwined with some further problems, these
being the product of the relatively small number of babies in the anal-
yzed sample. The final sample of twelve was chosen from the twenty
babies completing the study because it was felt these records were
least noisy and each experimental session was trouble free. (It was no
coincidence that almost all of this sample were among the last babies to
be run for the experiment.) In addition, as the experimenter became pro-
gressively more experienced with the Bayley as a tool, it was felt that
the later scoring reflected more reliable differences between the babies

on this dimension. The most apparent difficulty with this small number

28

is the significantly reduced power of the F-test used to define differ-
ences in the means between groups. By comparison to this sample,
Cousins (1976) used 128 children, with trials blocked in groups of

four. Research with infants always requires greater situational con-
trol than research with other subject populations, and also has a far
greater experimental mortality. The experimenter, in recognizing this,
made the decision to accept the reduced sample (and concomitantly
reduced statistical power) in order to be confident that the results
from the accepted sessions were obtained under as methodologically rig-
orous conditions as possible. As previously mentioned, the majority of
infants in these sessions had previously failed to finish a prior ses-
sion, and were judged to be a random sample on this basis. Another
problem with the small number of sampled infants is the restriction of
range on the Bayley Mental Scale scores. Even though the extremes of
the sample differed greatly, the highest scores in the low group, and
similarly the lowest in the high group, were quite close. One sep-
arate analysis was done excluding the score closest to the overall medi-
an in each Bayley group, but this result was also nonsignificant (p>’.10)
and no further analyses were done. A possible age confound is also due
to the small number of infants. Originally, the goal was to obtain far
more infants, as close to ninety days as possible. In the final sample,
although the mean was close to this age, the infants ranged from 90 to
122 days of age. Infant maturation during this period is both rapid,
and as the developmental shift from heart rate acceleration to stimulus
presentation to heart rate deceleration highlights, qualitatively differ-
ent over short periods. The time confound during this period is one

that possibly could further affect the results obtained, although, as

29

the analyses show, there was clear evidence of orienting in the sample.

Despite the majority of negative results, there was one stimulus,
the variability response to the tone, that discriminated between the high
and low Bayley groups (see Figure 5). The interpretation of this lone
significant result is difficult due to the inflated alpha level from run-
ning the large number of comparisons. (Similarly, interpretation of the
one significant variability change over time must also await replica—
tion.)

When proposing this study, the author felt that one of its contri-
butions was applying the use of variability analysis to the study of
individual differences in infancy. Since it was felt that variability
reflected a tonic rather than a phasic attentional response, it was
anticipated that differences on this measure would be most likely pres-
ent to stimuli that elicited a maximal tonic response, i.e., the infant
slide or the baby coo. However, equally attractive is the possibility
that this response is equivalent to stimuli with high elicitation poten-
tial, and that the true differences would appear to stimuli that do not
elicit intrinsic attention by some property of the stimulus, e.g., con-
trast. A possible extension of this would be that infants with greater
spontaneous attention would manifest greater environmental awareness and
thus relative precocity.

As mentioned previously, since this area of inquiry is relatively
recent, the experimenter decided to run a rate analysis and a variabil-
ity analysis for Bayley group by each of two visual stimuli (the infant
slide and blank) and by each of two auditory stimuli (the tone and the
baby coo). The rationale for this was that the pair of results, either

for the more salient or less salient stimuli, would offer stronger

30

evidence for this phenomenon than would a single results. However, the
two less salient stimuli were most likely nonequivalent, since it was
probable that the tone was noxious rather than nonaversive. In addi-
tion, the problem of an inflated alpha level is again prominent. Des-
pite these problems, obtaining significance in consideration of the data
collection problems strengthens this finding. In previous studies by
Maltzman and associates (Maltzman, 1967; Maltzman and Raskin, 1965;
Maltzman and Mandell, 1968), the investigators were able to distinguish
differences in semantic conditionability by adult groups separated on
the basis of their GSR response to an 110 db white noise burst which
was clearly an aversive stimulus. Although their discussion is in terms
of orienting responses, the result is possibly supportive of the pres-
ent finding using this type of stimulus. A derivation from this could
be that differences are reflected in the range of stimuli and environ-
mental events to which infants can produce a response that will facili-
tate the "taking in" of a stimulus rather than its rejection. Obvious-
ly, this would require much empirical testing.

One last test was done to check if initial variability, as a mea-
sure of spontaneous variability, was related to differences in the Bay
Bayley score. ~When arranged by high and low Bayley groups, there was no
relationship between these groups and the baseline variability (see
Table 15). This could also be due to any of the problems described, to
the different amount of time needed to acclimate infants, or, obviously,
the lack of a true relationship. Again, variability analyses are more
sensitive to measurement errors since random errors will inflate the
variance without affecting the group means (and therefore the deceler-

ation curves).

31

There are several ways in which either this or future studies could
be adapted to provide a better examination of the interaction between
biological and psychological variables during infancy. The Bayley
Scales are probably not the best instrument for evaluating individual
differences between young infants; the Brazleton Neonatal Behavioral
Assessment Scale (Brazleton, 1973) has been used in a number of recent
studies of infant behavior (e.g., Lester, Emory, Hoffman, and Eitzman,
1976), and appears to be a superior dependent variable for studies of
this type. The test has been designed to evaluate more global char—
acteristics of early infant behaviors, focusing mainly on a set of inte-
grative behaviors more complex than the simple items on the early ranges
of the Bayley scale. A recent paper (Lester, et al., 1976) reported an
"attentional-orientation" factor present in a varimax factor solution
on the Brazleton Scale administered to newborns (although in this sam-
ple of 54 infants, half were low birth weight children). An alterna-
tive approach to the use of a complex measure of many items (e.g., the
Bayley scales) would be using a single well defined dependent measure.
This approach has been advocated by Horowitz (1974) for the study of
individual differences in habituation during various experimental manip-
ulations (although Cousins ‘ [1976] study found no relationship between
cardiac response and habituation to a tactile stimulus).

A review of the most recent literature leaves little doubt that
studies of this type will become increasingly frequent in the future.
With the decreasing cost of high technology digital processors and asso-
ciated equipment, and the increasing sophistication of mathematical
models for evaluating psychophysiological data, studies virtually impos-

sible at the onset of the decade are becoming commonplace.

32

Psychophysiological techniques offer an excellent paradigm for the study
of biological-psychological interactions in early infancy, as well as
the study of developmental changes in maturation or certain psycholog-
ical processes. An excellent synthesis of these techniques is the
application of psychophysiological models to the problem of fetal moni-
toring during birth (Porges, 1978). Porges (1977) also has discussed
the use of these models for evaluating the functional maturation of the
autonomic nervous system, another useful application of these strate-
gies.

In summary, the present study can only add little to the literature
on individual differences in early infancy. It strongly reaffirms, howb
ever, the evidence for cardiac orienting in early infancy to a variety
of stimuli, and supports a defensive-orienting difference in cardiac
patterns. As mentioned above, many problems hampered this study, but
technological improvements being undertaken currently should eliminate
this problem for future studies in the Developmental Psychobiology Lab-
oratory. This area of interest should long be a fertile source of val—

uable research.

APPENDICES

APPENDIX A

APPENDIX A
Parental Consent Form

Background Information Form
Parental Feedback Form

33

Permission Form for Testing Infant

Date:

 

Dear Parents:

This form is to request permission for us or members of our staff to
examine your infant in tests of attention, and to administer the Bayley
Scales of Infant Development.

You may withdraw permission at any time simply by informing us or our
staff members that you wish to do so. The information collected is con-
fidential; it will be available only to qualified personnel, and infor-
mation on individual infants will be identified by number only. If

you have any questions about the procedures to be used, please feel

free to ask. The tests will not disrupt or in any way be harmful; howb
ever, participation in the study will not guarantee you or your infant
any beneficial results.

Your signature on this form verifies that the specific tests and proced-
ures to be used with your infant have been explained to your satis-
faction, and that you have voluntarily agreed to allow us to test your
infant. If at any time you wish to have the data for your baby with—
drawn from the study, simply advise us and we will destroy all records
relevant to your baby.

Any videotape record of the Bayley examination will not be viewed by
anyone except the experimenter and an assistant. The only use of this
will be to record the Bayley protocol, after which these records will
be destroyed.

Sincerely,
Steven R. Gitterman Hiram E. Fitzgerald, Ph.D.
Research Director Professor of Psychology

 

Parent's Signature

Experimenter's Signature

34

BACKGROUND INFORMATION SHEET

 

The information requested in this form will be used to report the gener-
al characteristics of the infants used in our research. Only group
results will be reported, and the identity of individual infants will
remain anonymous. All information you provide on this form will be kept
strictly confidential.

 

 

 

 

Infant Number Stimulus Order
Date of Test Time of Test
Tape Number Room Temperature

 

 

Experimenters:

 

Parents:

Date of Birth Sex: Male Female
Month Day Year

 

Place of Birth

 

 

 

City or Town State Country
Weight at Birth lb. oz. Length at Birth inches
Weight Now 1b. 02. Length Now inches
Due Date
Any complications during pregnancy? If so, please briefly

 

describe them.

Was medication used during labor and/or delivery (for example, local
anesthetic, gas, saddle block)? If so, please describe briefly.

Has your infant had any prolonged or general illness since birth?
If so, please describe briefly.

Has your infant received any medication since birth? If so, please
describe briefly.

 

 

 

Is your infant A bottle fed breast fed

some combination, with bottle feedinb 75% 50% 25%
Is this your first child? Yes No If no, how many children do
you have?

35

MICHIGAN STATE UNIVERSITY

 

DEPARTMENT OF PSYCHOLOGY EAST LANSING ' MICHIGAN ' 48824
SNYDER HALL

Dear Parents:

Please excuse the delay in my getting this letter out to you. Only
just recently have I been able to complete the scoring of all the heart
rate records, and then finish the laborious process of analyzing the
data.

In sum, the analysis of the data didn't work out quite as well as
I hoped. Most of the infants responded to the different stimuli with
the cardiac response typical of 3 months per age (a rapid acceleration,
then prolonged deceleration). Mbreover, the cardiac responses clearly
differentiated between the two auditory stimuli (the tone and the baby
sound) when they were presented. I've included a graph of both these
patterns on the second sheet.

Unfortunately, there was no relationship between the heart rate
patterns and the items from the Bayley infant test. There are probably
many reasons for this, not the least of which I'm sure was the amount of
time spent in the booth when the different stimuli were presented. There
are many ways in which this type of research can be improved, and from
this experience I hope we can strengthen future research in the lab.

Again let me thank you for coming down to the lab with your child.
As you might guess, it's very difficult to get subjects for this type
of research, and your participation, along with many others, has helped
to produce much successful work in this field. If there are any addi-
tional questions I can answer, please feel free to call me at 353-1651.

Sincerely yours,

Steve Gitterman

SG:sh

36

APPENDIX B

APPENDIX B

Analysis of Variance Summary Tables

37

Table 1
Analysis of Variance Summary Table for Heart Rate

to Blank Slide (seconds)

 

Source df MS F p

 

Between Subjects

Bayley Group (A) 1 144.075 .192 .671
Subject w. groups 10 750.584

Within Subjects

 

Time (B) 24 46.353 2.031 .004

B x Sub. w. grps. 240 22.818

A x B 24 25.601 1.122 .320
Total 299

38

Table 2
Analysis of Variance Summary Table for Heart Rate

to Baby Slide (seconds)

 

Source . df MS F p

 

Between Subjects

Bayley Group (A) 1 23.297 .027 .873
Subject w. groups 10 867.404

Within Subjects

 

Time (B) 24 57.848 2.017 .004

B x Sub. w. grps. 240 28.681

A x B 24 16.307 .569 .949
Total 299

39

Table 3
Analysis of Variance Summary Table for Heart Rate

to Baby Sound (seconds)

 

Source df MS F p

 

Between Subjects

Bayley Group (A) 1 67.100 .137 .719
Subject w. groups 10 490.696

Within Subjects

 

Time (B) 14 27.455 .554 .896

B x Sub. w. grps. 140 49.549

A x B 14 15.392 .311 .992
Total 179

40

Table 4
Analysis of Variance Summary Table for Heart Rate

to 250 Hz Tone (seconds)

 

Source df MS F p

 

Between Subjects

Bayley Group (A) 1 1.168 .003 .958
Subject w. groups 10

Within Subjects

 

Time (B) 14 14.932 .708 .764

B x Sub. w. grps. 140 21.096

A x B 14 19.480 .923 .536
Total 179

41

Table 5
Analysis of Variance Summary Table for Heart Rate

Variability to Blank Slide (period)

 

Source df MS F p

 

Between Subjects

Bayley Group (A) 1 19.508 .026 .874
Subject w. groups 10 739.600

Within Subjects

 

Period (B) 6 417.849 1.905 .095

B x Sub. w. grps. 60 219.390

A x B 6 33.032 .151 .988
Total 83

42

Table 6'
Analysis of Variance Summary Table for Heart Rate

Variability to Baby Slide (period)

 

 

 

Source df MS F p

Between Subjects

Bayley Group (A) 1 25.377 .044 .838

Subject w. groups 10 578.196
Within Subjects

Period (B) 6 309.969 .894 .505

B x Sub. w. grps. 60 345.671

A x B 6 298.851 .865 .526
Total 83

43

Table.7
Analysis of Variance Summary Table for Heart Rate

Variability to Baby Sound (period)

 

Source df MS F p

 

Between Subjects

Bayley Group (A) 1 47.277 .096 .763
Subject w. groups 10 491.067

Within Subjects

 

Period (B) 4 175.272 .686 .606

B x Sub. w. grps. 40 255.465

A x B 4 164.896 .645 .633
Total 59

44

Table 8
Analysis of Variance Summary Table for Heart Rate

Variability to 250 Hz Tone (period)

 

Source df MS F p

 

Between Subjects

Bayley Group (A) 1 2162.88 5.926 .035
Subject w. groups 10 364.981

Within Subjects

 

Period (B) 4 118.728 .558 .695

B x Sub. w. grps. 40 212.926

A x B 4 198.550 .932 .455
Total 59

45

Table 9

Analysis of Variance Summary Table for Heart Rate

Differences to Checkerboard and Blank (sec.)

 

 

 

Source df MS F p
Stimulus (A) 1 132.446 .262 .619
Error (A x S) 11 505.141
Time (B) 24 68.202 2.186 .002
Error (B x S) 264 31.199
AxB 24 12.662 .745 .803
Error (A x B x S) 264 17.006
Error (S) 11 1017.69
Total 599

46

Table 10
Analysis of Variance Summary Table for Heart Rate

Differences to Baby Sound and Tone (sec.)

 

 

 

Source df MS F p
Stimulus (A) 1 1163.52 4.139 .067
Error (A x S) 11 281.082
Time (B) 14 22.596 .651 .818
Error (B x S) 154 34.708
AxB 14 19.793 .606 .858
Error (B x S) 154 32.684
Error (S) 11 539.306
Total 359

47

Table 11

Analysis of Variance Summary Table for Heart Rate Variability

Differences to Checkerboard and Blank Slide (period)

 

 

 

Source df MS F p
Stimulus (A) 1 240.913 .556 .472
Error (A x S) 11 433.362
Period (B) 6 555.880 1.500 .192
Error (B x S) 66 370.565
A x B 6 133.975 .872 .521
Error (A x B x S) 66 153.707
Error (S) 11 1339.88
Total 167

48

Table 12

Analysis of Variance Summary Table for Heart Rate Variability

Differences to Baby Sound and 250 Hz Tone (period)

 

 

 

Source df MS F p
Stimulus (A) 1 116.427 .285 .604
Error (A x S) 11 408.172
Period (B) 4 104.124 .509 .730
Error (B x S) 44 204.728
A x B 4 189.695 .746 .566
Error (A x B x S) 44 254.150
Error (S) 11 570.884
Total 119

49

Table 13
Analysis of Variance Summary Table for Heart Rate

Difference to Baby Slides (sec.)

 

 

 

Source df MS F p

Baby Slides (A) 1 822.979 1.059 .325
Error (A x S) 11 776.877

Time (B) 24 50.260 1.945 .006
Error (B x S) 264 25.846

A x B 24 22.846 .860 .657
Error (A x B x S) 264 25.597

Error (8) 11 679.545

Total 599

50

Table 14
Analysis of Variance Summary Table for Heart Rate

Variability Differences to Baby Slides (period)

 

 

Source df MS F p
Baby Slides (A) 1 444.178 2.829 .121
Error (A x S) 11 157.045
Period (B) 6 261.994 1.254 .291
Error (B x S) 66 208.984
A x B 6 125.811 .521 791
Error (A x B x S) 66 241.682
Error (S) 11 534.9219
Total 167

51

Table 15
Menn-Whitney U Test for Differences

in Initial Variability by Bayley Group

Z = 0.5, p>'.10

52

APPENDIX C

.- :11! .prr_ ‘_’

III.-

 

APPENDIX C

Figures

53

Figure 1. Heart rate change to the auditory stimuli. Second 1 is the

first second after stimulus presentation.

 

 

’43 ° "
I”
IE]:~ - '1
‘~ I. -
ed "
“
‘\
o n ‘
\
\
O h —I
I
o h "'
\
_ \
. ‘CJ -
'6: [1”
. d
D ‘\‘
FE? . “:3\ ~
0 u-
)3
It. —
\
\
O D . _,..:l.'.'ln
m 0 uli-’"’ .'
z ’7’" —
o o )3 °
l- 0 I
D o q
l I 1 l 1 l l l L I L l l
IO N - ' 7 N I?
n

('NIW 83d $1V38 ) 39NVHO 31W!

54

8. IO. l2. l4.

8 ECONDS

6.

Figure 2. Variability change to blank slide presentation. Each period

is a five second interval; the first interval is the five second inter-

val prior to stimulus onset, the last interval is the five second

interval after stimulus offset.

.Pmom .- 5. man. a: 0033....

 

N .0 0 ..v .n .N
— p . _ d . . . . _
\ II
\ o I/ o
I \\\ I
. d1
s o
u
n. 30..
O :0...

N Mano...—

0.N

0.0

0.0.

0.3

0.0.

 

All'llBVIHVA

55

Figure 3. Heart rate change to the checkerboard and blank stimuli.

Second 1 is the first second after stimulus presentation.

 

 

 

O D .-Ԥ~~
.-
x!
z o
83 D.
5.. - tr):
- a-"
. ‘33
0 I,”
. ”’4|
o In
to ’-—U
o I~Z
2 '~ --
D ’.’
(.9 n‘
E " ~.
~..
‘.
‘5
‘ I
x
- “an -
v,- '
vvd‘fi""
I
l l l l l l I l l l I l l
e no. '0. n. '0. a
. - v '0 3*

('NIW 83d SlVBB ) 39NVHO sum

56

20.

I6.

l2.

SECONDS

Figure 4. Heart rate change to the two baby slides. Baby A was always
presented prior to Baby B. Second 1 is the first second after stimulus

presentation.

 

 

o D P °
< m EL ' "
>. o
S In uh. ..
4 < ’
m m ‘ I
all "‘
v .1
~~~p . -
d o
v ,[j . ..
E 53a ‘
e .5 .
"' 1::
t1.-_ -
~~~~D 0‘
b -
’o’b .
’0’" o d
- o
o I .-
l l l l l l l l
o 0 0. 0. 0. 0.
oi N e» 39 «p

('NIW 83:! 813738) BONVHO 31V!

57

I6. 20. 24.

I2.
SECONDS

Figure 5. Variability change to the 250 Hz tone divided by Bayley
group. Each period is a five second block; period 1 is the five second

interval before stimulus presentation. Period 5 is the five second

interval after stimulus presentation.

n. 30..
O 20....

bmon. no. man a. . 00.1w...

n N
A . . .

n manor.

0.N

0.0

o. 0.
V’ O

All'IIBVIHVA

0.
o

0.NN

0.0M

 

58

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