Schedule-induced escape from fixed-interval reinforcement

Pigeons trained to peck one of two keys for food were exposed to an ascending and descending series of fixed-interval values. A response on the second key produced an escape period consisting of a visual stimulus change. During escape periods, the fixed-interval timer continued to operate and even if it timed out, a response on the food key would not operate the feeder unless preceded by an escape-key response that terminated the escape condition. As the fixed-interval schedule was increased logarithmically through six values from 30 to 960 sec, the percentage of session time spent in escape as well as the frequency, duration, and rate of escape increased to a maximum and then decreased. One subject did not develop escape behavior to any significant degree. For all pigeons, escapes usually occurred after, rather than before, reinforcement.     

Lateral masking for letters with unlimited viewing time

Linear arrays of 1, 8, and 9 letters were exposed while S read off the items of the letter sequence while maintaining constant fixation. By this procedure, serial position effects were studied in the absence of requirements for scanning the array quickly, as in a tachistoscopic display, and for remembering a large number of items, as in a delayed whole report. Despite the absence of these requirements, typical serial position curves were generated. Serial position effects were partially ameliorated by the introduction of blank spaces into the array. Performance was influenced both in the immediate vicinity of the blank spacings, as well as extending over a large portion of the array. The data were interpreted in terms of lateral masking effects associated with adjacent elements.     

A feature utilization analysis of the perception of pattern class structure

Patterns were computer-generated about two prototypes to form schematic clusters of three diameters about the cluster centroids. In a schematic concept-formation task, recovery of a priori schematic class membership by Os varied inversely as physical cluster diameter, with concept acquisition across trials evidenced in only the low-cluster-diameter condition. For each 0 who failed to classify according to the schema rule, linear discriminant function analysis was applied to his classes. In all cases, O-generated classes were successfully recovered by the physical pattern features used as predictors, the mapping of these classes by the LDF exceeding that by the schema rule in accuracy at all cluster-diameter levels.     

Feature encoding and pattern classifications with sequentially presented Markov stimuli

The major objective of this experiment was to develop and evaluate a methodology designed to permit more direct assessment of the detailed processes involved in prototype abstraction. Thirty Ss participated in a task having the following characteristics: (1) classifications of Markov-generated stimuli sampled from two different populations, (2) controlled scanning of pattern features, (3) a measure of the degree to which pattern features were correctly identified, and (4) intermittent reproduction of pattern features abstracted from collections of mixed instances. Results showed that a significant number of the Ss learned to classify the stimuli into categories corresponding to generation rules and, at least partially, abstracted the population prototypes from these variable instances. The feature identification data suggested that the Ss who were unsuccessful in classifying the stimuli into the rule-defined categories used an inappropriate strategy for sampling pattern information upon which to base their classifications.     

Coping with drinking pressures: adolescent versus parent perspectives

Fifteen techniques to limit or stop alcohol consumption were rated by 94 adolescents, aged 12 to 19, and their parents. Factor analysis of effectiveness ratings demonstrated consistency in appraisal of adult options for coping strategies, but significant differences in adolescent and parent views of how teenagers should cope with drinking pressures.