The effects of feature extinction in dual-response feature-positive discriminations.

In a typical feature-positive discrimination, responding is reinforced (+) during the target stimulus (A) on trials with the feature stimulus (X), but not during target-alone trials (A-). When X and A are presented simultaneously, direct control by X is typically observed; however, when the stimuli are presented serially, X sets the occasion for responding to A. In the current dual-response procedures, one response (e.g., left lever press) was reinforced during feature-target trials (XA+) and a different response (e.g., right lever press) was reinforced during target-alone trials (A+). In Experiment 1, rats received either serial (X → A+) or simultaneous (X:A+) presentations of the feature-target compound along with target-alone trials (A+). Contrary to our predictions, the serial group failed to learn the discrimination and the simultaneous group demonstrated occasion setting. In Experiment 2, the salience of the feature was increased, which resulted in direct control by the feature in both groups. In Experiment 3, an additional serial group was included with a longer interval between the feature (X) and target (A). Despite the reduced temporal proximity of X to reinforcement, direct control was again observed in all groups. The current pattern of results in the simultaneous and serial groups is interpreted in relation to the enhanced salience of A relative to X, due to separate pairings of A-alone with reinforcement in the dual-response procedure. Consistent with previous findings, occasion setting was observed when A was most salient relative to X (Experiment 1, simultaneous group), but direct control was found when the salience of X was increased (Experiments 2-3). (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Properties of iconic and visuospatial working memory in pigeons and humans using a location change-detection procedure.

Tests of visuospatial memory following short (<1 s) and medium (1 to 30 s) delays have revealed characteristically different patterns of behavior in humans. These data have been interpreted as evidence for different memory systems operating during short (iconic memory) and long delays (working memory). Leising et al. (2019, Behavioural Processes, 169, Article 103957 ) found evidence for both systems in pigeons and humans completing a location change-detection task using a visual mask that disrupted accuracy following a short (100 ms), but not a long (1,000 ms) delay. Another common finding is that adding to-be-remembered items should disrupt accuracy after a long, but not short, delay. Experiments 1a and 1b reported this memory system crossover effect in pigeons and people, respectively, tested on location change detection with delays of 0, 100, and 1,000 ms and displays of two to 16 items. Experiments 2a and 2b reported that the color of the items had little (pigeons) or no (humans) effect on change-detection accuracy. Pigeons tested in Experiment 3 with longer delays (2,000, 4,000, and 8,000 ms) and large set sizes demonstrated the crossover effect with most displays but did not demonstrate an abrupt drop in accuracy characteristic of iconic memory. In Experiment 4, accuracy with novel types of change (color, shape, and size) was better after a 0-ms delay and above-chance levels on color and shape trials. These data demonstrate the memory system crossover effect in both humans and pigeons and expand our knowledge of the properties of memory systems across species.