Psychophysical scaling of stimulus similarity in 3-month-old infants and adults

The ability of 3-month-old infants to discriminate novel components of a prefamiliarized stimulus was assessed using an operant paradigm. Subjects were familiarized with the standard stimulus (five-component mobile) in three daily conditioning sessions and then were exposed to a comparison mobile containing from zero to four novel components substituted for familiar elements at the outset of a fourth daily session. Although a reliable reduction in mean number of footkicks was found only when an extreme number of components was substituted, log-log plots of infant response as a function of degree of novelty indicated that discriminability was described by a power function. Adult judgments of the similarity between the standard mobile and each degree of novelty were also described by a power function, suggesting a common basis may underlie the perception of similarity in the two groups. The finding of a power function for infant response to visual novelty is consistent with reports of similar discriminability functions in infant olfaction and audition. However, duration of visual fixation increased nondifferentially to all test stimuli, irrespective of degree of novelty. The latter finding is inconsistent with predictions arising from the visual attention literature.     

Measuring the reliability of observational data: a reactive process

Reliability of observational data was measured simultaneously by two assessors under two experimental conditions. During overt assessment, observers were told that reliability would be measured by one of the two assessors, thus permitting computation of reliability with an identified and an unidentified assessor. During covert assessment, observers were not informed of the reliability measured. Throughout the study, each of the assessors employed a unique version of a standard observational code. In the overt assessment condition, reliability of observers with the identified assessor was consistently higher than reliability with the unidentified assessor, indicating that observers modified their observational criteria to approximate those of the identified assessor. In the covert assessment condition, reliability with the two assessors was substantially lower than during overt assessment. Further, observers consistently recorded lower frequencies of disruptive behavior than the two assessors during covert assessment.     

Time discrimination training of laboratory animals using a PDP-8 computer

The purpose of this paper Is to describe the use of a small, general-purpose digital computer system in the training of laboratory animals to discriminate stimuli on the basis of their duration. The computer hardware and software required for such training, together with some illustrative results from two recent studies, will be described.     

Clothing: Communication, Compliance, and Choice

This study looks at some effects of five different styles of women's clothing: Formal Skirt, Formal Pants, Casual Skirt, Casual Pants, and Jeans. There were no significant differences in compliance to a request to fill out a questionnaire made by experimenters dressed in the five clothing styles, although experimenter age and sex effects were found. Ratings of photographs of the five dress styles indicate that a model was viewed by both male and female subjects as most happy, successful, feminine, interesting, attractive, intelligent, and wanted as a friend when wearing a Formal Skirt outfit and as least so when wearing Jeans. She was also seen as more active when wearing pants as compared with a skirt. Subjects' reasons for choosing what clothing to wear did not indicate that how one will appear to others is the major factor in clothing selection. It appears that clothing does communicate something about the wearer but may influence behavior toward her primarily in the absence of other information about her status.     

A cryogenic implant for producing reversible functional brain lesions

This paper describes a permanently implanted device for applying cold to localized parts of the brain surface in order to produce reversible functional lesions in behaving animals. It consists of an array of several independently controlled stainless steel tubing loops, each shaped to fit a separate brain area. Cooled alcohol is pumped through the tubing and temperatures are monitored with attached thermocouples. Implanted loops can be cooled to 0°C within 15 sec, and temperatures can be maintained at ±1°C of accuracy. Tissue tolerance is excellent: Implants have been demonstrated to last up to 1 year or more. Methods and materials for construction are discussed.