A cellular analogue of operant conditioning.

Using the hippocampal-slice preparation, we attempted to model operant conditioning in vitro by reinforcing pyramidal cell bursting responses with local micropressure applications of transmitters and drugs. The same injections were administered independently of bursting to provide a "noncontingent" control for direct pharmacological stimulation or facilitation of firing. The results suggested that the bursting responses of individual CA1 pyramidal neurons may be reinforced in a dose-related manner by response-contingent (but not noncontingent) injections of dopamine and the selective dopamine D2 agonist, N-0923. N-0924, a stereoisomer of N-0923 that is largely devoid of D2-agonist activity, failed to reinforce CA1 bursting. Burst-contingent injections of the excitatory neurotransmitter glutamate also failed to reinforce CA1 bursting; indeed, the glutamate applications (whether contingent or random) reduced the likelihood of bursts while increasing the frequency of solitary spikes. Reinforcement delays exceeding 200 ms largely eliminated the reinforcing efficacy of the D2 agonist N-0437 in CA1 operant conditioning. The results are consistent with the suggestion that the behaviorally reinforcing effects of dopaminergic agents can be modeled in vitro in the hippocampal-slice preparation.     

Eudoxos and Dedekind: On the ancient Greek theory of ratios and its relation to modern mathematics

This material is based upon work supported, in part, by the National Science Foundation under Grant No. DIR-8808575.     

Recognition hypermnesia: The growth of recognition memory (d') over time with repeated testing

This study sought to determine whether recognition hypermnesia (unforgetting) might be obtained over time with repeated testing of recognition memory. Four types of stimuli were investigated: pictures or words (captions) from configured (funny) or non-configured (non-funny) cartoons. Three recognition tests, each comprising the same stimulus and distractor items, were successively administered after the presentation of a large set of captioned cartoons. Silent think intervals of 5 min were interpolated between recognition tests. Recognition hypermnesia, measured by increasing d' estimates of accessible recognition memory, was obtained with the pictures from configured (funny) cartoons but not with any of the other groups.     

GROUPCOM: A computer program for investigating social processes in small groups

A flexible computer program for conducting on-line social psychological research is described. Using cathode-ray tube terminals, two to six subjects can communicate with one another, or one to six subjects can “communicate” with one to nine simulated others. In the latter case, the simulated information received by each subject can be independently manipulated. The experimenter has control over several features of the experimental trials, including response order, response type, method of response collection, and display format. The program can be used to investigate phenomena such as conformity, reaction to deviance, social comparison of abilities, group decision making, impression management, and leadership.     

SOME ETHICAL CONSIDERATIONS OF SHORT-TERM WORKSHOPS IN THE PRINCIPLES AND METHODS OF BEHAVIOR MODIFICATION1

Workshops and seminars to expose different sectors of the professional community to the principles and applications of behavior modification are briefly discussed. The possible misapplication of procedures by conference participants, whose only exposure to behavioral methods has been at these workshops is viewed as a potentially serious ethical issue. It is suggested that the goals of such seminars and workshops must be clarified, and methods of evaluation of the participants' skills devised, lest we contribute to the misapplication of procedures and to the criticism that behavioral methods are unethical approaches to treatment.     

Differential reinforcement of low rates performance by impulsive and reflective children

Third-grade boys classified as either cognitively impulsive or reflective were reinforced for key pressing according to a DRL (differential reinforcement of low rates) 6-sec schedule of reinforcement. Half of each group received instructions about the behavioral requirements for obtaining reinforcements. Prior to DRL training, impulsive Ss showed a low probability of key press responding at long interresponse time (IRT) intervals while reflective Ss exhibited an equal probability of terminating either short or long IRTs. During training and in the absence of instructions, impulsives exhibited a less precise temporal discrimination, characterized by a greater predominance of response bursts (0–2 sec IRTs) following reinforcements, than reflective Ss. While impulsive and reflective Ss displayed similar frequencies of collateral behavior between successively reinforced responses, impulsives engaged in the reinforced response more frequently and tended (p < .08) to obtain fewer reinforcements. Instructions served to enhance the DRL performance.     

Elaboration and knowledge acquisition

Memory & Cognition - Three experiments that explored the effects of different types of elaboration on knowledge acquisition are presented. The materials used were adapted from Stein and...     

Constraints on the processing of indirect speech acts: evidence from aphasiology

The ability of anterior aphasics and patients with right-hemisphere damage to comprehend both the literal and nonliteral readings of indirect speech acts was examined. Subjects viewed videotaped episodes in which one actor asked another “Can you X?” and the second actor responded with either an action or a simple “Yes.” Subjects judged whether the response was appropriate given its context. Anterior aphasics could comprehend the nonliteral but not the literal reading, supporting models that posit that people have direct access to nonliteral but conventional readings. Patients with right-hemisphere damage could appreciate the direct reading, but failed to distinguish between appropriate and inappropriate action-responses. This finding suggests that it may be possible to dissociate the pragmatic and syntactic aspects of comprehension of indirect speech acts.