Auditory evoked potentials and sex-related differences in brain development

Auditory evoked potentials (AEPs) were obtained to probe tones which were delivered during the presentation of complex verbal and nonverbal auditory stimulation to 3-month-old infants. Significant sex-dependent AEP amplitude asymmetries were found. Females produced higher-amplitude responses from the left hemisphere and males produced higher-amplitude responses from the right hemisphere during both the verbal and nonverbal presentations. No significant AEP asymmetries were obtained in an independent group of infants that received only the probe tones. These findings are consistent with theories and behavioral data suggesting differences between males and females in the development of language and spatial functions.     

Binocular disparity as a discriminable stimulus parameter for young infants

The ability of 8-week-old infants to discriminate between projected stereograms with and without retinal disparity was tested with an habituation-dishabituation paradigm. Infants in two experimental groups received six trials with either the disparity or the nondisparity stimulus and then were given two trials with the other display. Infants in two control groups viewed the same stimulus, either disparity or nondisparity, on all eight trials. There was a suggestion of some response decrement over time in both cardiac deceleration and sucking suppression, although this effect was not significant. However, significant increment was obtained on the dishabituation trials for heart rate in the group that was shifted from the nondisparity to the disparity stimulus. These results were interpreted as indicating that the infants could discriminate between stimuli when the only difference between them was binocular disparity.     

Remembering a criminal conversation: beyond eyewitness testimony

Unlike the important body of work on eyewitness memory, little research has been done on the accuracy and completeness of "earwitness" memory for conversations. The present research examined the effects of mode of presentation (audiovisual/ auditory-only) on witnesses' free recall for utterances in a criminal conversation at different retention intervals (immediate/delayed) within a single experiment. Different forms of correct recall (verbatim/gist) of the verbal information as well as different types of errors (distortions/fabrications) were also examined. It was predicted that participants in the audiovisual modality would provide more correct information, and fewer errors than participants in the auditory-only modality. Participants' recall was predicted to be impaired over time, dropping to a greater extent after a delay in the auditory-only modality. Results confirmed these hypotheses. Interpretations of the overall findings are offered within the context of dual-coding theory, and within the theoretical frameworks of source monitoring and fuzzy-trace theory.