Development of a complex multiple schedule in the chimpanzee

The development of chimpanzee behavior on a four-component, three-lever multiple schedule is described. Component schedules included the Sidman avoidance procedure with a concurrent discriminated avoidance schedule on a second lever, fixed ratio performance for food, differential reinforcement of low rate for water requiring a dual response chain, and a symbol discrimination task for continuous food reinforcement using three levers. The avoidance component of this schedule was employed during the January 31, 1961 suborbital space flight of the chimpanzee “Ham.” On November 29, 1961, the chimpanzee “Enos” performed on the multiple schedule during three orbits around the earth in a Mercury capsule.     

Work planning and performance review as a basis for merit pay decisions: An evaluation

The Work Planning and Performance Review (WPPR) System, developed in a midwestern state as a basis for pay-for-performance decisions in the state government, is described. The WPPR's job relevance was evaluated in one state agency by comparing WPPR scores with scores on a behavioral checklist developed for that purpose. Supervisor and subordinate perceptions of the relevance of the two systems are described. Comparison and perception data indicate the WPPR lacks content validity. Probable impact on the merit pay system is discussed.     

Auditory perception of temporal and spectral events in patients with focal left and right cerebral lesions

The auditory perception of temporal and spectral information was studied in subjects with lesions in the temporoparietal region of the left (LH group), or right (RH group) hemisphere (n = 5 in each group) and in five normal controls. The temporal tasks included gap detection and two complex pattern perception tasks in which subjects had to identify the placement of the two closest tones (separated by the shortest interval) within a sequence of six tones. The spectral tasks involved pitch matching and frequency discrimination. The results showed a "double dissociation": (1) the LH group was impaired in their ability to perceive temporal information, but the perception of spectral information was normal, and (2) the RH group was impaired in their ability to perceive spectral information, but the perception of temporal information was normal. The findings are consistent with the notion that temporal processing is a function of left-hemisphere structures and that spectral processing is a function of right-hemisphere structures.     

List-strength effect: I. Data and discussion

Extra items added to a list cause memory for the other items to decrease (the list-length effect). In one of the present studies we show that strengthening (or weakening) some items on a list harms (helps) free recall of the remaining list items. This is termed the list-strength effect. However, in seven recognition studies the list-strength effect was either absent or negative. This held whether strengthening was accomplished by extra study time or extra repetitions. The seven studies used various means to control rehearsal strategies, thereby providing evidence against the possibility that the findings were due to redistribution of rehearsal or effort from stronger to weaker items within a list. Current models appear unable to predict these results. We suggest that different retrieval operations underlie recall and recognition, as in the SAM model of Gillund and Shiffrin (1984), which can be made to fit the results with certain relatively minor modifications.     

List-strength effect: II. Theoretical mechanisms

Ratcliff, Clark, and Shiffrin (1990) examined the list-strength effect: the effect of strengthening (or weakening) some list items upon memory for other list items. The list-strength effect was missing or negative in recognition, missing or positive in cued recall, and large and positive in free recall. We show that a large number of current models fail to predict these findings. A variant of the SAM model of Gillund and Shiffrin (1984), involving a differentiation hypothesis, can handle the data. A variant of MINERVA 2 (Hintzman, 1986, 1988) comes close but has some problems. Successful variants of a variety of composite and network models were not found (e.g., Ackley, Hinton, & Sejnowski, 1985; Anderson, 1972, 1973; Metcalfe Eich, 1982; Murdock, 1982; Pike, 1984). The results suggest constraints on the future development of such models.     

Reverse versus forward recall of script-based texts

Previous research has shown that witnesses who are instructed to recall a crime scenario in reverse order as well as in forward order retrieve more total information than witnesses who recall in forward order twice. The present experiment evaluated the hypothesis that forward recall consists of schema-based retrieval whereas reverse-order recall consists of more datadriven, non-schematic retrieval. It was predicted that more actions consistent with a scenario's schema would be recalled in forward order than in reverse order, more actions incidental to the schema would be recalled in reverse order than forward order, and more schema-based intrusions would be generated in forward order. The results confirmed these predictions. Implications for witness interviewing are discussed.     

The effects of majority size on minority influence

Two experiments investigated the role of majority size (social pressure) in minority influence. Opposite predictions were derived from an attributional account and two social impact models. In Experiment 1 there was a tendency for minority influence to decrease with increasing majority size when the minority argued against gay rights. The results were stronger and clearer in Experiment 2. For pro-abortion minorities, the minority's impact clearly declined as the size of the opposing majority increased. As predicted by the social impact models, this decline occurred during the initial increase of the majority size. The limitations of the mathematical models are discussed.     

An experimental study of the relationship between thoughts and eating behaviour in bulimia nervosa

This study tested the hypothesis that cognitive disturbance has a causal role in the maintenance of disturbed eating in bulimia nervosa. Thoughts about eating, weight and shape were activated in one group of patients with bulimia nervosa (the experimental group) but not in another (the control group). There was an increase in negative self-statements in the experimental group following the experimental manipulation. Food consumption was then measured in a taste test. As predicted, the experimental group ate less in the short term than the control group. Contrary to expectations, they did not subsequently report more objective bulimic episodes as a consequence of this decreased food intake. They did, however, report significantly fewer subjective bulimic episodes.     

Men's and women's self-confidence in persuasive,comforting, and justificatory communicative tasks

The self-confidence of men and women was assessed in three types of interpersonal communicative situations. Participants indicated anticipated level of success, evaluated their performance, and assessed the extent to which the outcome was due to ability and to effort. The most striking finding was higher self-confidence in women than in men in comforting tasks. No difference emerged in level of self-confidence between men and women in persuasive tasks. Men tended to anticipate more success in justifying decisions, but following their performance, did not rate either the quality of the performance or their ability higher than did women.