Infants’ sensitivity to the depth cue of shading

Five- and 7-month-old infants were tested for sensitivity to the depth cue of shading. Infants were presented with two displays: a surface in which a convexity and a concavity were molded and a photograph in which shading specified a convexity and a concavity. Each display was presented under both monocular and binocular viewing conditions. Reaching was observed as the dependent measure. Infants in both age groups reached preferentially for the actual convexity in both the monocular and binocular viewing conditions. In the monocular photograph condition, the 7-month-olds reached preferentially for the apparent convexity specified by shading, indicating that they perceived it to be an actual convexity. These infants showed no significant reaching preference in the binocular photograph condition. This finding rules out interpretations of the infants’ reaching not based on perceived depth. The results therefore suggest that the 7-month-olds perceived depth from shading. The 5-month-olds showed no significant reaching preferences when viewing the photograph; thus, they showed no evidence of depth perception from shading. These findings are consistent with the results of a number of studies that have investigated infants’ sensitivity to pictorial depth cues. Together, these studies suggest that the ability to perceive depth from pictorial cues may first develop between 5 and 7 months of age.     

Quantitative assessment of infant reaching movements

We have identified a fundamental property of human motor behavior as a tight coupling of the curvature-speed relationship in the reaching movements of 5- to 9-month-old infants. This relationship termed a movement unit, occurs regardless of the distance of duration of the reach and in spite of the developmental change that occurs in grasping during this period. Movement unit durations are tightly clustered around 200 ms regardless of overall duration or distance or the position of the unit in the reach. The curvature-speed coupling has been identified by others in adult reaching and handwriting. Models of biological motor control must account for this invariant relationship.     

Lay knowledge of eyewitness behaviour: A British survey

One of the recent concerns in the study of eyewitness memory is how well lay knowledge, i.e. ‘common sense’, matches the findings of empirical research. A number of American and Canadian studies, some using questionnaire methodology, have found limitations in lay knowledge of eyewitness behaviour. Further studies have extended this general finding beyond the lay public–who are prospective jurors–to legal professionals such as lawyers and policemen. The present study utilized the Knowledge of Eyewitness Behaviour Questionnaire (KEBQ), an inventory used in previous studies, to replicate the North American studies with a British sample of students, including law students, and the general public. The results showed a great similarity between the North American and British samples' knowledge of eyewitness behaviour. A significant number of correct responses were made to eight of the 14 KEBQ items, with a significant number of incorrect responses to the remainder. It was also found that law students were no more knowledgeable than other subjects; that knowledge did not vary with age; and that previous experience as an eyewitness was not related to knowledge of eyewitness behaviour. In responding to some of the criticisms of questionnaire studies it is argued that the evidence is mounting in favour of the need for a recognized system to make jurors aware of the factors known to influence eyewitness testimony.     

Time went by so slowly: Overestimation of event duration by males and females

In three experiments, 469 subjects watched a short videotape of a bank robbery and later estimated the duration of the tape. Subjects invariably overestimated the durations. Accuracy of time estimation was unrelated to amount of free recall (Experiment 1) or accuracy of memory (Experiment 2). Females overestimated to a greater degree than males (Experiments 2 and 3). A more stressful version of the event produced greater overestimates than a less stressful version (Experiment 3). The relationship between induced arousal and time estimation appears to be different for men and women.     

Referrals to school psychologists: A national survey

School psychologists serving a national, systematic sample of public elementary and secondary schools were surveyed regarding recent referrals. Most referrals were initiated by school staff members (75% of referrals), and the majority occured initially through formal mechanisms (55% of referrals). Most informal requests for assistance or information eventually became, or were thought likely to become, formal referrals. In 92% of cases, the referral agent's initial communication with the psychologist included some designation of what the pupil was doing or not doing that was viewed as problematic. Poor academic performance was of primary concern in 52% of referrals and social/emotional problems in 31%. More boys were referred than girls, and one-half of referrals from the elementary grades involved pupils in grades K-2. Frequency of referral and reason for referral were not independent of pupil's grade or sex. Reason for referral was independent of time of year (October vs. May) and geographical region.     

Discrepancy detection and vulnerability to misleading postevent information

When people are exposed to misleading details after a witnessed event, they often claim that they saw the misleading details as part of the event. We refer to this as themisinformation effect. In four experiments, involving 570 subjects, we explored the role that discrepancy detection plays in the misinformation effect. Experiment 1 showed that subjects who naturally read a post-event narrative more slowly were more resistant to the effects of misleading information contained in the narrative. In Experiment 2, subjects who naturally read more slowly were more likely to detect a discrepancy between what they were reading and what was stored in their memory. In Experiment 3, subjects who were instructed to read slowly were more likely to detect a discrepancy than were those who were instructed to read quickly. In Experiment 4, subjects who were instructed to read slowly were more resistant to misleading postevent information. Taken together, these results suggest that longer reading times are associated with a greater scrutiny of postevent information. This leads to an increased likelihood that discrepancies will be detected and that the misinformation will be resisted.