Age and sex differences in the cooperative and noncooperative behavior of pairs of American children

Game playing behavior of same and mixed sex pairs of 5-, 8-, and 11-year-old American children was compared, using a game in which cooperative behavior maximized reward. Pairs of 8- and 11-year-old children were relatively more cooperative and attained significantly more Joint Reward Goals than 5-year-old pairs. Older pairs were not maximally cooperative, however, in terms of all the dependent measures; in adjusting for initial differences on practice trials, 5-year-olds and 8-year-olds took less time than the 11-year-olds, and 11-year-old pairs of boys took significantly more time than all other pairs. In addition, cooperative behavior increased across trials, especially for the 11-year-old children.     

Characteristics of dropouts, remainers, and refusers at a psychosocial rehabilitation program for the chronically mentally disabled

Thirty-eight chronically mentally disabled patients who were invited to join a newly established, vocationally oriented, day treatment program in Raleigh, North Carolina, served as subjects. We attempted to determine whether demographic and psychosocial characteristics significantly differed among groups of clients who dropped out of, remained in, or refused membership in this community-support program. A variety of demographic, expectancy, psychological, and psychosocial measures were administered to each subject. Most significant was the finding that the subjects' perceived level of help and support from friends was a significant determinant of the level of program participation. Those subjects who refused to participate (refusers) perceived themselves as receiving proportionately less support than did members of the other two groups (dropouts and remainers).     

An infrared system for the detection of a pigeon''s pecks at alphanumeric characters on a TV screen: the dependency of letter detection on the predictability of one letter by another.

Three pigeons pecked at letters of the alphabet and at the symbol "?" displayed on a computer-driven cathode ray screen. A 4 by 4 matrix of infrared emitting and detecting diodes and associated circuitry identified the location of a pigeon''s responses to the screen. Responses at the target letter T were probabilistically reinforced with food whenever T appeared in a string of three letters in the middle of the screen. Responses at the symbol "?" appearing below this string were probabilistically reinforced whenever T did not appear. The letter F anywhere in the three-character string either strongly predicted the occurrence of the target letter T, in two conditions, or predicted its nonoccurrence, in a third. This manipulation of the frequency with which the familiar letter F predicted T was shown to change the function relating probability of a correct peck at the symbol "?" to the number of Fs in the string. This effect may be interpreted as an instance of the phenomenon where an organism''s acquired knowledge changes what it sees.     

Discriminated interresponse times: role of autoshaped responses.

When discriminated interresponse-time (IRT) procedures have been used to assess preference relations among temporally extended operants, deviations from matching have been obtained. Using a yoked-control procedure, the present study found that key pecking in a discriminated IRT procedure has two sources of strength--that arising from the response-reinforcer contingency that is explicitly arranged, and that arising from a stimulus-reinforcer contingency that is a by-product of the explicitly arranged contingency. The key pecking of all lead birds, and that of 3 of the 4 birds exposed to a yoked autoshaping procedure, was controlled by the keylight that signaled the lead birds' criterion IRTs. Because stimulus control of key pecking by the keylight, whether autoshaped or discriminative, fosters deviations from matching, the discriminated IRT procedure does not provide an appropriate basis for conclusions about preference relations among IRTs.     

Differential effects of electroconvulsive shock on concurrent spatial memories: "old" memories are impaired while "new" memories are spared

The effects of electroconvulsive shock (ECS) on spatial memory first reported by Shavalia, Dodge, and Beatty (1981, Behavioral and Neural Biology, 31, 261-273) were systematically replicated in two experiments. Rats acquired concurrent spatial memories in two 8-arm radial mazes. Each rat was allowed four choices in Maze 1 and then, after 2 h, four choices in Maze 2. After 2 h each rat was tested for retention in Maze 1 and, after 2 more h, was tested for retention in Maze 2. A single ECS was administered immediately after the fourth choice in Maze 2. Retention (as measured by accuracy of Choices 5-8) was diminished for Maze 1 but not for Maze 2. In the second experiment, the delay between the retention tests was eliminated (thus holding the ECS-Choice 5 interval constant for the two mazes). Once again retention of Maze 1 was impaired and retention of Maze 2 was spared; that finding suggests that ECS does not proactively affect radial-arm maze performance. The results of a third experiment converge on the same conclusion; ECS failed to reduce levels of spontaneous alternation. Therefore, ECS appears to interfere retroactively with relatively old spatial memories and newly established memories appear to be immune to the amnestic effects of ECS. Implications and various explanations are considered.     

Hippocampal stimulation disrupts spatial working memory even 8 h after acquisition

The present experiment used hippocampal stimulation to determine the temporal gradient of consolidation of spatial working memory. Rats were trained to perform a spatial working memory task on a radial maze with 12 arms. Each rat went to the ends of 6 arms to obtain a food reward. After 8 h, the rat chose among all the arms to find the ones not previously chosen (and consequently still having food). During some test sessions, the hippocampus was stimulated electrically either at a current level just high enough to produce an electrophysiological seizure, or at a current level below this seizure threshold. Stimulation occurred at one of five intervals (0 to 8 h) following the completion of the first six choices. During other test sessions, the hippocampus was not stimulated. After seizure stimulation, the number of retroactive errors (returning to arms chosen prior to stimulation) increased at all delay intervals; the number of proactive errors (returning to arms chosen after stimulation) increased only with the delay of 8 h. Subthreshold stimulation had no influence on either type of error. These results indicate that normal hippocampal function is required for the maintenance of spatial information in working memory, and that the time course of consolidation of this information is significantly greater than that seen in other types of memory, or consolidation may not take place at all.     

Levels of processing and picture memory: the physical superiority effect

Six experiments studied the effect of physical orienting questions (e.g., "Is this angular?") and semantic orienting questions (e.g., "Is this edible?") on memory for unrelated pictures at stimulus durations ranging from 125-2,000 ms. Results ran contrary to the semantic superiority "rule of thumb," which is based primarily on verbal memory experiments. Physical questions were associated with better free recall and cued recall of a diverse set of visual scenes (Experiments 1, 2, and 4). This occurred both when general and highly specific semantic questions were used (Experiments 1 and 2). Similar results were obtained when more simplistic visual stimuli--photographs of single objects--were used (Experiments 5 and 6). As in the case of the semantic superiority effect with words, the physical superiority effect for pictures was eliminated or reversed when the same physical questions were repeated throughout the session (Experiments 4 and 6). Conflicts with results of previous levels of processing experiments with words and nonverbal stimuli (e.g., faces) are explained in terms of the sensory-semantic model (Nelson, Reed, & McEvoy, 1977). Implications for picture memory research and the levels of processing viewpoint are discussed.     

Some effects of color on naming and recognition of objects

In this article, we investigated the role of color in the recognition and naming of everyday objects. In the first experiment we found that color pictures were named faster than black-and-white and that shape information did not facilitate color naming. Experiment 2 was carried out to determine at which stage of object processing the color facilitation occurred. We found that color had no effect on object recognition but did facilitate object naming, even when color was redundant for discrimination. This did not apply to naming abstract shapes. Experiment 3 replicated the findings of Experiment 2 using different objects and colors. The results showed that color could facilitate but not inhibit object naming and did not affect object recognition.