Teaching apes to ape language: explaining the imitative and nonimitative signing of a chimpanzee (Pan troglodytes)

Fifteen videotaped conversations of a chimpanzee signing with his trainers were examined in order to determine (a) whether the ape was using imitation to learn about new language forms as some human children do and (b) whether the ape's nonimitative utterances implied knowledge of linguistic structures. The answers to both questions were negative. The evidence suggests that the utterances lacked the semantic and syntactic organization found in the utterances of most children. Instead of learning to use signs as symbols for communicating propositional messages, the ape learned to use gestures as nonsymbolic instrumental responses under the stimulus control of objects in the signing context and verbal and nonverbal cues from the trainers. Other research now underway with chimpanzees may eventually reveal whether this performance is characteristic of chimpanzees in general or is the result of particular training strategies used to teach language to chimpanzees.     

The effects of social comparison on ability evaluations

Investigated the effects of comparisons with similar and dissimilar performances on estimates of relative ability. Male and female undergraduates (n = 162) took a test of analogy-making ability, and received veridical feedback about their own performance and manipulated feedback about the scores of other college students. Supporting Festinger's similarity hypothesis, variations within a range of small discrepancies between self and others' scores produced significant changes in ability estimates, while variations within a range of large discrepancies had no significant impact. This pattern of results only held for discrepancies relative to the modal score of others, and not relative to their highest or lowest scores. There were also indications that subjects with average performances were less influenced by the comparison feedback than were subjects with low or high scores. The discussion focused on the similarities and contrasts between seeking comparison information versus being influenced by it.     

Type A behavior, need for control, and reactions to group participation

The present study examines the behavior of Type A coronary-prone subjects in group problem-solving sessions. Subjects discuss possible solutions to two problems in same-sex groups containing both Type As and Bs. As are much more likely than Bs to be seen as leaders and are rarely nominated as the least helpful member. Although A and B leaders are both seen as moderately likeable, A leaders' problem solutions are rated as lower in quality. Manipulations of problem importance and incentive for good solutions have similar effects on As and Bs. The results are discussed as being generally consistent with the proposal that Type As are primarily motivated by a need for control. Some indirect support is obtained for the idea that As are more susceptible than Bs to learned helplessness.     

The need for contextual and technical knowledge in judgmental forecasting

The purpose of this research is to assess the extent to which judgmental forecasts are improved by having more contextual and technical knowledge. Contextual information is knowledge gained by practitioners through experience on the job, consisting of general forecasting experience in the industry as well as specific product knowledge. Technical knowledge is knowledge about data analysis and formal forecasting procedures, including information on how to analyze data judgmentally. We directly compared judgmental forecasts of business practitioners with those generated by students, using 22 real-world time series. The practitioners had considerable contextual but no technical knowledge. The students had no contextual but two different levels of technical knowledge. We also generated forecasts with statistical methods to benchmark performance. Results show that contextual knowledge is particularly important in making good judgmental forecasts, while technical knowledge has little value. Practitioner forecasts are better than student forecasts in almost all comparisons. A decisive factor affecting forecast performance appears to be data variability, measured by the coefficient of variation of the time-series data. As the variability of a time series increases, the performance of all forecasts deteriorates, but judgmental forecasts by practitioners become more preferable. Statistical methods have difficulty achieving reasonable forecasts when the data are more variable, whereas judgemental forecasts reinforced by contextual information do relatively well. Data variability is one explanation for the mixed findings of past studies, relative to how well statistical techniques compare with judgment as a forecasting method.     

Sex differences in performance and hemispheric organization for a nonverbal auditory task

Musically experienced and inexperienced men and women discriminated among fundamental-frequency contours presented either binaurally (i.e., same contour to both ears) or dichotically (i.e., different contours to each ear). On two separate occasions, males made significantly fewer errors than did females in the binaural condition, but not in the dichotic condition. Subjects with prior musical experience were superior to musically naive subjects in both conditions. The dichotic pitch task produced a left-ear advantage, which was unrelated to gender or musical experience. The results suggest that the male advantage on the binaural task reflects a sex difference in the coordination of the two hemispheres during conjoint processing of the same stimuli rather than a difference in the direction or degree of hemispheric specialization for these stimuli.     

Childhood depression and conduct disorder: I. Behavioral, affective, and cognitive aspects of family problem-solving interactions.

We assessed the family interactions of depressed, conduct-disordered, mixed depressed-conduct-disordered, and nonclinic children, ages 7-14 years, during a standardized family problem-solving discussion in the clinic. The child's and the mother's problem-solving proficiency, aversive behavior, and associated affective behavior (depressed and angry-hostile) were observed. The child and mother also rated each other's affect during the interaction for the dimensions sad, angry, critical, and happy on Likert-type scales. The child's and mother's cognitive constructions about the interaction were assessed using video-mediated recall. Although all clinic groups had lower levels of effective problem solving than did nonclinic children, their deficiencies were somewhat different. Mixed and depressed children displayed high levels of depressed affect and low levels of angry affect, whereas conduct-disordered children displayed both angry and depressed affect. In addition, conduct-disordered children had lower levels of positive problem solving and higher levels of aversive content than did non-conduct-disordered children. Depressed and conduct-disordered children had higher levels of self-referent negative cognitions than did mixed and comparison children, and depressed children also had higher other-referent negative cognitions than did all other groups. The study provides support for theories and treatment that stress the importance of family problem-solving and conflict resolution skills in child psychopathology.     

Perceptual processing and speed-accuracy trade-off.

Three experiments are described on speed-accuracy trade-off during a visual fixation. In a typical trial subjects started by fixating a fixed position at their left side at which a degraded digit (SL) was presented. At about the same time an intact digit (SR) was briefly presented at a fixed right side position. SL and SR were separated by a binocular visual angle of 45 degrees. The task was to verbally report both digits, which implied that the eyes should be rapidly shifted from SL to SR, so as not to miss SR. Under these conditions the distribution of the fixation latencies of SL appeared to consist of two parts, suggesting the occurrence of either anticipations or reactions. This argues against a strategy of optional stopping of information accrual during the fixation of SL and is in line with a strategy of either fully neglecting or fully encoding SL. However, this interpretation meets the difficulty that, at trials where SL is reacted to, subjects showed a shorter fixation latency than in a control condition, in which they had ample time to view both SL and SR. The results of the second and third study supported the view that, when under time stress, subjects can end a fixation as soon as a preliminary code of SL is obtained. This code (a) is insensitive to the complexity of SL, (b) cannot be elaborated during the saccade to SR, and (c) can be used as a starting point for further analysis, as soon as the eyes reach SR.     

The Effects of Group Discussion on Eyewitness Accuracy

Previous research on group performance in judgmental tasks reveals that groups are rarely inferior, and often superior, to the average individual. The present study examined whether this pattern of results extends to the accuracy of eyewitness reports of a crime. It was found that group discussion led to accounts that were significantly more accurate than the average individual. A requirement to reach a unanimous decision did not alter any of the effects of group discussion. Group superiority was especially clear in terms of the completeness of the reports and in estimations of the duration of the incident. The discussion considered the implications of the present results for the current practice of prohibiting group discussion as an aid to the preparation of testimony.     

Wilhelm Wundt and the cognitive shift

This paper compares Wundtian and cognitive psychology with respect to immediate and mediate experience, non-functionalism, and the status of the experiment. It is pointed out that the perspective of immediate experience, which can also be found in early American functionalism, has disappeared in the wake of behaviorism. Next cognitive psychology, which to some extent represents a correction of behaviorism, is compared with Wundt's system. It is concluded that in spite of certain similarities the Wundtian and the cognitive perspective are irreconcilably opposed.