A psychometric study of positive and negative nominations and the pupil evaluation inventory

Two peer evaluation measures, the Pupil Evaluation Inventory (PEI) and positive and negative nominations were compared in a sample of 260 children in grades 1 to 5. Stabilities of the measures were assessed over a 4-month period. In the total sample, PEI factors and negative nominations were more stable than positive nominations, and PEI Aggression and Withdrawal scores were more stable than negative nominations. PEI Aggression and Withdrawal scores were more stable in grades 3 and 5 than in grade 1, and the Likability factor was more stable in grades 2 to 5 than in grade 1. Negative nominations were most strongly correlated with the PEI Aggression factor, and positive nominations were more strongly correlated with Likability than with Aggression. Implications for the use of these nomination measures are discussed.During the writing of this report Charlotte Johnston was supported by a doctoral fellowship from the Social Sciences and Humanities Research Council of Canada. The authors wish to express appreciation to Dr. Edward Vertuno and to all the staff, teachers, and children of the Developmental Research School, Florida State University, whose cooperation made this research possible.     

The influence of expertise on X-ray image processing

Observers with four different levels of radiological experience performed a recognition memory task on slides of faces and chest X-ray films. Half of the X-ray films revealed clinically significant abnormalities and half did not. Recognition memory for faces was uniformly high across all levels of radiological experience. Memory for abnormal X-ray films increased with radiological experience and, for the most experienced radiologists, was equivalent to memory for faces. Surprisingly, recognition memory for normal films actually decreased with radiological experience from above chance to a chance level. These results indicate that radiological expertise is associated with selective processing of clinically relevant abnormalities in X-ray images. Expert radiologists appear to process X-ray images the way that we all process faces, by quickly detecting and devoting processing resources to features that distinguish one stimulus from another. However, the selective processing of X-ray films appears to be restricted to clinically relevant abnormalities. As they develop the ability to detect these abnormalities, radiologists appear to lose the ability to detect variations in normal features.     

Social mediation of puberty: an adaptive female strategy?

Females of two hamster species with contrasting degrees of gregariousness were tested for social influences on the timing of sexual maturation. When female dwarf hamsters (Phodopus sungorus campbelli), a gregarious species, were housed with an adult male at weaning, they began estrous cycles significantly earlier than when they were housed alone or with their family. Females housed with one or two female siblings at weaning matured significantly later than did all other females. Once mature, females housed with familiar males conceived later than did females housed with unfamiliar males. Rearing conditions also affected body weight; those housed with female siblings grew more slowly and attained a lower weight at 8 weeks of age than did females in all other groups. In contrast, when weanling female golden hamsters (Mesocricetus auratus), a solitary species, were housed with either an adult male, two female siblings, or alone, they did not differ in their rate of sexual maturation or growth. It is suggested that the degree to which social factors can accelerate or delay puberty is an adaptive characteristic and may be correlated with the degree of gregariousness of a species.     

Middle temporal cortical visual area and visuospatial function in Galago senegalensis.

Bushbabies with lesions restricted to the middle temporal (MT) area and animals with larger extrastriate lesions including area MT were compared with normal control animals on test of visuospatial localization and discrimination learning. Ablation of area MT was sufficient to produce impairments in directing behavior appropriately on the basis of visuospatial cues. Extension of the lesion into areas 18 and 19 produced more profound deficits. Retardation in learning a stripe discrimination problem was correlated with the extent of damage to the geniculostriate system. It is hypothesized that area MT is important in achieving and maintaining fixation on a target whereas cortical areas 18 and 19 are necessary for establishing the location of stimulation in visual space.     

Alterations of male sexual behavior by learned aversions to hamster vaginal secretion

Male hamsters poisoned after their first adult exposure to the vaginal secretion of female hamsters became hesitant to approach and ingest the secretion. The same aversion-training procedure also altered the responses of males to estrous females, changing the latency, frequency, and duration of a variety of behaviors that are commonly taken as indexes of sexual attraction or arousal and of copulatory performance. The effects suggest that the aversions to vaginal secretion alter the perceived meaning of the secretion for male hamsters, and analysis of the correlations between various measures of sexual arousal and performance support the hypothesis that separate mechanisms underlie the effects of the secretion on appetitive and consummatory sexual behavior.     

Perceptual processing of nontargets in an attention task

The capability of nontargets to qualitatively influence the semantic processing of coincident targets was investigated in three experiments. Subjects were aurally presented a series of word pairs and attempted to detect homonymic instances of a predesignated category (e.g., animals). The nontarget with which a target (e.g., ANT) was paired was appropriate (e.g., CRAWLING), inappropriate (e.g., UNCLE), or neutral (e.g., STRAW). Experiments 1 and 2 established that detection of targets can be facilitated by appropriate nontargets and inhibited by inappropriate ones. Thus, nontargets can influence the way in which targets are semantically represented. Experiment 3 showed that this effect is eliminated when subjects are precued as to the ear of entry of targets. Thus, precuing appears to curtail the perceptual processing of nontargets. The data run counter to theories that claim that focused attention does not entail the perceptual suppression of nontargets.     

Infants' discrimination of faces by using biological motion cues

We report two experiments in which we used animated averaged faces to examine infants' ability to perceive and discriminate facial motion. The faces were generated by using the motion recorded from the faces of volunteers while they spoke. We tested infants aged 4-8 months to assess their ability to discriminate facial motion sequences (condition 1) and discriminate the faces of individuals (condition 2). Infants were habituated to one sequence with the motion of one actor speaking one phrase. Following habituation, infants were presented with the same sequence together with motion from a different actor (condition 1), or a new sequence from the same actor coupled with a new sequence from a new actor (condition 2). Infants demonstrated a significant preference for the novel actor in both experiments. These findings suggest that infants can not only discriminate complex and subtle biological motion cues but also detect invariants in such displays.     

Higher order pattern structure influences auditory representational momentum

Representational momentum refers to the phenomenon that observers tend to incorrectly remember an event undergoing real or implied motion as shifted beyond its actual final position. This has been demonstrated in both visual and auditory domains. In 5 pitch discrimination experiments, listeners heard tone sequences that implied either linear, periodic, or null motions in pitch space. Their task was to judge whether the pitch of a probe tone following each sequence was the same or different from the final sequence tone. Results suggested that listeners made errors consistent with extrapolation of coherent pitch patterns (linear, periodic) but not with incoherent (null) ones. Hypotheses associated with internalized physical principles and pattern-based expectations are discussed.