The effects of within-group and between-group methodologies in the study of perceptions of infant crying

Recent studies have indicated that various infant cry patterns can be reliably distinguished when directly compared with other infant cry patterns. The purpose of this study was to compare the effects of this within-group method of cry presentation (in which listeners are exposed to 2 types of cry patterns) with the effects of a between-group methodology (in which listeners are exposed to only 1 type of infant cry pattern). 4 groups of adult listeners rated the tape-recorded cries of low- and high-risk infants on 4 Likert-type scale items during experimental phases. In phase 1, subjects were exposed to either the cries of low-risk or high-risk infants but not both. In phase 2, subjects were exposed to both low-risk and high-risk infant cries. In phase 3, subjects were exposed to the cries they heard in phase 1. Whereas all scale items differentiated the low- and high-risk infant cries during the within-group analyses of phase 2, all scale items did not differentiate low- and high-risk infant cries during the between-group phase of the experiment. The specific pattern of results indicate that within-group methods of cry presentation accentuate the perceptual distance among cry types and may actually create many reliable differences that would not be found in between-group comparisons.