Increased novelty-induced grooming in aged rats: a preliminary observation

Age-related changes in grooming activity in female Fischer-344 rats were observed in a home cage and in a novel testing chamber for 50 min. Compared to the home cage condition with brief handling treatment, excessive grooming was found in the novel situation. The amount of novelty-induced grooming of aged rats (26-28 months) was about two times that of young animals (6-8 months). This increase in novelty-induced grooming of aged animals was attributable to an increase in the number of grooming bouts, prolongation of each grooming bout, and a slight increase in the duration of licking elements. However, there were no age differences in the percentage of face washing and the duration of face-washing elements. These results are discussed in terms of behavioral aging and age-related changes in peptidergic pathways in the brain.     

Interrogative suggestibility and delinquent boys: An empirical validation study

This study has several aims. First, to validate the Gudjonsson Suggestibility Scale (GSS) among delinquent and adolescent boys placed in an assessment and short-term treatment centre. Second, to test the hypothesis that adolescent boys are particularly susceptible to suggestions when they are ‘pressured’ by negative feedback and instructions. Finally, to investigate the hypothesis that suggestibility is related to memory recall and self-esteem. The GSS was administered to 31 boys (ages 11 to 16 yr) who had been independently rated by two teachers on measures of suggestibility and self-esteem. Suggestibility as measured by the GSS was found to correlate significantly with the teachers' ratings of suggestibility, supporting empirically the criterion-related validity of the GSS. Compared with young ‘normal’ adults the boys were no more likely to give in to suggestive questions than the adults, unless their performance was subjected to criticism and negative feedback. The results suggest that deliquent adolescents may be particularly responsive to interpersonal pressure during interrogation. The findings have important implications for police interrogation procedures.     

The effects of empathic instructions upon donating behavior: Sex differences in young children

First-grade children were given either empathy instructions (in which they were told to imagine themselves in the target person's place) or neutral instructions (in which they were told to listen to what the target person did). For half the subjects, the target person was of the same sex; for the other half, the target person was of the opposite sex. Subjects were then given a chance to anonymously donate money to the target child, who was presented as being in need. Liking for the target child, subject's perceptions of the target child's emotional state, and subjects' report of their own emotional states were also assessed. Empathic instructions increased donating behavior for males, but not for females. Accuracy of perception of the target person's state was generally high. Self-reports of emotional states congruent with that of the target tended to be associated with increased donating behavior only for males, but these self-reports were greater for females than males, and greater for both sexes with same-sex target persons. Liking also was enhanced by gender similarity. These results are discussed in terms of a proposed relationship among empathy, prosocial behavior, sex, and age.We wish to express our gratitude to the staff and students of Wannamaker and North Fairview Elementary Schools of Topeka, Kansas, for their assistance in carrying out this research, and also thank C. Daniel Batson for his helpful suggestions and comments.     

Motor programme information as a separable memory unit

Summary Two experiments produced further evidence for the claim that motor programme information may be considered as a separate memory unit, partially independent of other memory representations. In Experiment 1, it was shown that for the comparison of shared movement components in two actions such as turning the handle and stirring the ingredients, the activation of their motor programmes is required. This is demonstrated by the finding that the execution of the first action, which preactivates its motor programmes, leads to shorter reaction times than under control conditions in which the verbally described action is only spoken. In Experiment 2, it was further shown that the execution of the action does not in every case expedite the assessment of a connection between a prime item and a target item vis à vis verbal repetition, but only where the task requires the activation of motor programmes.     

Odor recognition: familiarity, identifiability, and encoding consistency

The investigation examined the association between the perceived identity of odorous stimuli and the ability to recognize the previous occurrence of them. The stimuli comprised 20 relatively familiar odorous objects such as chocolate, leather, popcorn, and soy sauce. Participants rated the familiarity of the odors and sought to identify them. At various intervals up to 7 days after initial inspection, the participants sought to recognize the odors among sets of distractor odors that included such items as soap, cloves, pipe tobacco, and so on. The recognition response entailed a confidence rating as to whether or not an item had appeared in the original set. At the time of testing, the participants also sought to identify the stimuli again. The results upheld previous findings of excellent initial recognition memory for environmentally relevant odors and slow forgetting. The results also uncovered, for the first time, a strong association between recognition memory and identifiability, rated familiarity, and the ability to use an odor label consistently at inspection and subsequent testing. Encodability seems to enhance rather than to permit recognizability. Even items identified incorrectly or inconsistently were recognized at levels above chance.     

Representation of linear orders

Two binary classification tasks were used to explore the associative structure of linear orders. In Experiment 1, college students classified English letters as targets or nontargets, the targets being consecutive letters of the alphabet. The time to reject nontargets was a decreasing function of the distance from the target set, suggesting response interference mediated by automatic associations from the target to the nontarget letters. The way in which this interference effect depended on the placement of the boundaries between the target and nontarget sets revealed the relative strengths of individual interletter associations. In Experiment 2, students were assigned novel linear orders composed of letterlike symbols and asked to classify pairs of symbols as being adjacent or nonadjacent in the assigned sequence. Reaction time was found to be a joint function of the distance between any pair of symbols and the relative positions of those symbols within the sequence. The effects of both distance and position decreased systematically over 6 days of practice with a particular order, beginning at a level typical of unfamiliar orders and converging on a level characteristic of familiar orders such as letters and digits. These results provide an empirical unification of two previously disparate sets of findings in the literature on linear orders, those concerning familiar and unfamiliar orders, and the systematic transition between the two patterns of results suggests the gradual integration of a new associative structure.     

Detection versus discrimination of visual orientation

The role of focused attention in vision is examined. Recent theories of attention hypothesize that serial search by focal attention is required for discrimination between different combinations of features. Experiments are reported which show that the mixture of a few (less than five) horizontal and vertical line segments embedded in an aggregate of diagonal line segments can be rapidly counted (also called 'subitizing') by a parallel (preattentive) process, while the discrimination between horizontal and vertical orientation requires serial search by shifting focal attention to each line segment. Thus detecting and counting targets that differ in orientation can be done in parallel by a preattentive process, whereas knowing 'what' the orientation of a target is (horizontal or vertical, ie of a single conspicuous feature) requires a serial search by focal attention.     

Rapid error correction during human arm movements: evidence for central monitoring

Studies were made of rapid error correction movements in eight subjects performing a visually guided tracking task involving flexion-extension movements about the elbow. Subjects were required to minimize reaction times in this two-choice task. Errors in initial movement direction occurred in about 3% of the trials. Error correction times (time from initiation to reversal of movement in incorrect direction) ranged from 30-150 ms. The first sing of correction of the error movement was a suppression of the electromyographic (EMG) activity in the muscle producing the error movement. This suppression started as early as 20-40 ms after the initiation of the error-related EMG activity and as much as 50 ms before any overt sign of limb movement. The correction of the error movement was also accompanied by an increase in the drive to the muscle which moved the arm in the correct direction. This increased activity always occurred after the initiation of the error movement. it is concluded that the first step in the error correction, suppression of drive to the muscle producing the error movement, cannot be based on information from the moving limb. It is thus suggested that this earliest response to the error movement is based on central monitoring of the commands for movement.