Infants’ observing and heart period responses as related to novelty of visual stimuli

Abstract

No justification was found for computing an average reliability estimate although fairly high interobserver correlations were obtained for judgments of infants' fixation times.No intrastimulus decrement was found in observing times, whereas heart period responses when adjusted for prestimulus levels showed across-trial changes, but differentially for males and females. Relationships between observation duration and degree of interstimulus nove lty were contingent upon stimulus sequence and tended to be nonmonotonic.In this initial experiment with infants on the psychophysiology of visual stimulus novelty, both observing and cardiovascular responses were recorded to determine if these were systematically related to novelty, one of Berlyne's (1960) "collative" properties. Two conceptualizations of novelty are used here. The first, "intrastimulus novelty, I I involves repeated presentation of a given stimulus; degree of novelty is assumed to decrease with repeated exposure of this stimulus. The effects of such a procedure, if they occur, are often termed habituation, or more descriptively, response decrement. The second notion, I 'interstimulus novelty, I I entails a comparison of different stimuli, some having been familiarized to various degrees. The present study had two major purposes: (a) to assess interobserver reliability in judging infants' ocular fixation responses; and (b) to examine the relationship of intrastimulus and inter stimulus novelty to observing time scores and to cardiac reactivity. MethodThe results are based on data obtained from 24 Ss, 12 males and 12 females, each 5 months old (± 1 week).S sat in an infant seat facing a 12-1/2 x 12-1/2 in. projection screen located 24 in. away. The stimulicolored pictures of a ball, a bear, a clown, and a dollwere projected onto the screen by a Dunning Animatic strip film projector. The objects occupied approximately 50 sq. in. of the 120 sq. in. light field illuminated by the projector. Two peep holes in the screen, 6 in. apart, allowed two observers to view the infant.The EKG was transduced from chest and back leads into a Fels Cardiotachometer to monitor heart rate. A pulse coincident with the R-wave triggered a Hewlett-Packard counter and printer which timed the successive R-R intervals or heart periods and printed them with stimulus codes.Interstimulus novelty was varied by presenting the clown, ball, bear, and doll pictures differential numbers of times. A given stimulus was projected for four trials (phase 1). Then a new stimulus was introduced and the Psychon. Sci., 1966, Vol. 5 (6) two stimuli were each presented four times (phase 2). Subsequently, a third stimulus was added (phase 3),and finally a fourth (phase 4), each stimulus appearing four times within a given phase. Thus, after 40 trials, the relative presentation frequencies (presumably from the least to the most novel stimulus) were 16, 12, 8, and 4 projections. Four counterbalancing groups insured that each of the four stimuli appeared for the first time in each of the four phases. A 9 se...

Sex differences in infant habituation research: A survey and some hypotheses

“…Friedman et al (1974) demonstrated decremented visual fixation and subsequent recov-ery of fixation to a highly discrepant stimulus for both sexes, but found that only the female newborns showed response recovery to a moderately discrepant stimulus. Monitoring cardiac responses, Meyers and Cantor (1966) found that female infants' heart rate decelerations decreased with repeated stimulus presentations, evidencing reduced attention, while the males'decelerations increased in frequency over the course of the experiment. With regard to sex differences in the opposite direction, Cohen et al ( , 1971 and Pancratz and Cohen (1970) found that males', but not females', visual flXations habituated with repeated viewing of a stimulus.…”

“…Thirty-four of the 72 studies reviewed produced data pertinent to the issue of sex differences. Of these, seven (21%) found sex differences in habituation: Four investigations showed that rate of habituation and/or degree of discriminative response recovery were greater for male infants (Cohen, DeLoache, & Rissman, 1975;Cohen, Gelber, & Lazar, 1971;Cornell & Strauss, 1973;Pancratz & Cohen, 1970), while three demonstrated superior female perfonnance (Caron & Caron, 1969;Friedman, Bruno, & Vietze, 1974;Meyers & Cantor, 1966).…”

Individual differences in the infant's distribution of attention to stimulus discrepancy.

“…A second methodological strategy has involved short-term familiarization and testing of changes in attentional indexes within one brief session. Generally, these studies also suggest that duration of attention is greater to novel than to familiar stimuli (Fantz, 1964;Meyers & Cantor, 1966, 1967Saayman, Ames, & Moffet, 1964; but see Lewis, Bartels, Fadel, & Campbell, 1966). In each supporting case, however, the result was qualified by an interaction with familiarization rate, class of stimuli, sex, or specific stimulus preferences.…”

Habituation Rate and the Infant's Response to Visual Discrepancies

“…Finally, some investigators have observed sex differences in habituation to simple visual stimuli (Horowitz & Paden 1969;Meyers & Cantor 1966;Pancratz & Cohen 1970), and some have found sex differences in the response to novel stimuli (e.g., Meyers & Cantor 1967;Pancratz & Cohen 1970).…”