Interval and ratio reinforcement of a complex sequential operant in pigeons

Pigeons were required to produce exactly four pecks on each of two keys in any order for reinforcement. Correct response sequences were reinforced on either fixed-interval two-minute or fixed-ratio four schedules, with each correct sequence treated as a single response. Each pigeon developed a particular dominant sequence that accounted for more than 80% of all sequences. Sequence stereotypy was relatively unaffected by the temporal properties of the fixed-interval and fixed-ratio schedules. Response time (time from the first response in each sequence to the last) was also relatively unaffected by the temporal properties of the schedules. In contrast, response latency (time from end of one sequence to the beginning of the next) was markedly affected by the schedules. Latencies were long early in the interreinforcement interval and got shorter as the interreinforcement interval progressed. These data suggest that stereotyped response sequences become functional behavioral units, resistant to disruption or alteration by reinforcement variables that ordinarily influence the temporal spacing of individual responses.     

Verbal ability and mental processing speed

The notion that verbal ability is related to mental processing speed was examined using tasks that systematically varied in semantic content. Subjects' reaction times were measured in five tasks involving arrow matching, physical identity word matching, or taxonomic identity word matching. The findings indicated that matching tasks using different decision rules and different stimuli were all related to verbal ability. In fact, reaction time for subjects required to judge whether two arrows pointed in the same direction was the best predictor of verbal ability. One explanation of the results is that speed of information processing (a general factor) may be the important component of verbal ability which is measured by seemingly different matching tasks.     

SUPPRESSION OF SELF-STIMULATION: THREE ALTERNATIVE STRATEGIES

Four boys with autistic-like behavior were treated for self-stimulatory behavior with three different treatment procedures—time-out, differential reinforcement of other behavior (DRO), and overcorrection. All four boys showed a rapid response to the overcorrection procedure. Three boys demonstrated some evidence of decrement in responding with time-out. During the DRO procedure, one showed a modest decrease, two showed no change, but one exhibited a consistent increase in responding under this condition. A multiple baseline applied to one of the subjects failed to reveal any generalization of suppression from one setting to another. A strong but not perfect relationship was found between a frequency and a duration measure of self-stimulation. There was some evidence of negative side effects for one boy during overcorrection and for another during time-out. None of these negative side effects was enduring. There was also some indirect evidence that overcorrection facilitated appropriate play.     

Chunking in recall of symbolic drawings

Three experiments explored memory for symbolic circuit drawings using skilled electronics technicians and novice subjects. In the first experiment a skilled technician reconstructed circuit diagrams from memory. Recall showed marked “chunking”, or grouping, by functional units similar to Chess Masters’ recall of chess positions. In the second experiment skilled technicians were able to recall more than were novice subjects following a brief exposure of the drawings. This advantage did not hold for randomly arranged symbols. In the third experiment the size of chunks retrieved systematically increased with additional study time. Supplementary analyses suggested that the chunking by skilled subjects was not an artifact of spatial proximity and chunk statistics, and that severe constraints are placed on any explanation of the data based on guessing. It is proposed that skilled subjects identify the conceptual category for an entire drawing, and retrieve elements using a generate-and-test process.     

Increasing Career Center Accessibility for the Blind

To improve career planning services for visually impaired persons, the career center at Florida State University developed a self-directed program. This article describes strategies for making career information materials and resources more accessible to the blind.     

SELF-STIMULATION AND LEARNING IN AUTISTIC CHILDREN: PHYSICAL OR FUNCTIONAL INCOMPATIBILITY?1

This study investigated whether an observed inverse relationship between self-stimulation and learning in autistic children is due to a physical inability of the subject to use the same body part for self-stimulation and task responding, or whether self-stimulation “distracts” the subject from task responding. Four actively self-stimulating autistic children were taught two discrimination tasks; one required a response that physically interferred with their self-stimulation; the other did not. Results were: (a) all subjects responded similarly across both tasks; (b) the three subjects with higher mental age scores learned both tasks without external suppression of self-stimulation; and (c) none of the subjects showed an inverse relationship between self-stimulation and learning. The study demonstrated that elimination of self-stimulation is not a necessary prerequisite for the acquisition of a new behavior in all autistic children.     

Further examinations of the category-recall function

Subjects were assigned to use either three or six categories and were given either 5 or 10 trials in a word-sorting task. Subsequent to sorting, they recalled as many words as they could. A measure of sorting consistency showed that the six-category sort was a more difficult task than was the three-category sort. Number of categories did not have a significant effect on recall performance regardless of whether 5 or 10 sorting trials were used. A correlational analysis raised questions about the relationship of the sorting tasks to recall performance and clustering.     

Modification of the rat's acoustic startle response by antecedent visual stimulation.

Male hooded and albino rats were exposed to a light flash followed at various temporal intervals by a startle-eliciting 117 db. (re 20 muN/m2) burst of white noise. The visual stimulus engendered startle response inhibition (maximally when the lead time was 64-250 msec) as well as startle response latency reduction (maximally when the lead time was 2-8 msec). The temporal functions for the effects of visual stimuli paralleled those previously reported for startle modification by acoustic events. Further study revealed that, given optimal lead times, inhibition is produced reliably by weaker visual stimuli (3 X 10-6 cd-sec/cm2) than latency reduction (3 X 10-4 cd-sec/cm2). This differential sensitivity to visual stimuli is also analogous to previously reported findings for events in the acoustic environment. It reveals that the neural mechanisms that mediate latency reduction and inhibition can be engaged by either acoustic or visual stimulation.