Temporal discrimination in a long operant chamber

Animal Learning & Behavior, 2000

Learning & Behavior, 2006

Past evidence that pigeons may adopt a single-code/default strategy to solve duration sample discriminations may be attributable to the similarity between the intertrial interval (iTi) and the retention interval. The present experiments tested whether pigeons would adopt a single-code/default strategy when possible iTi-retention-interval ambiguity was eliminated and sample salience was increased. Previous studies of duration sample discriminations that have purported to show evidence for the use of a single-code/default coding strategy have used durations of 0, 2, and 10 sec . however, the results of experiment 1 suggest that the use of a 0-sec sample may produce an artifact resulting in inadvertent present/absent sample matching. in experiment 2, when pigeons were trained with three nonzero duration samples (2, 8, and 32 sec), clear evidence for the use of a single-code/default strategy was found.

Journal of the Experimental Analysis of Behavior, 1992

In each of two experiments, 2 pigeons received discrimination training in which food reinforcement for key pecking was conditional upon both spatial and temporal cues. In Experiment 1, food was available for periods of 30 s at each of three locations (pecking keys) during trials that lasted 90 s. In Experiment 2, food was available for periods of 15 min at each of four locations (pecking keys) during a 60-min trial. In both experiments, pigeons' key pecking was jointly controlled by the spatial and temporal cues. These data, and other recent experiments, suggest that animals learn relationships between temporal and spatial cues that predict stable patterns of food availability. Key words: spatial cues, temporal cues, time-place learning, foraging, key peck, pigeons This research was supported by the Natural Sciences and Engineering Research Council of Canada. Kevin Lee, Anita Lee, and Piers Samson assisted with the research.

1998

Abstract In conditional discriminations, when samples differ only in duration, pigeons typically show a choose-short effect (ie, higher matching accuracy on short-duration-sample than on long-durationsample trials with increasing delay between sample and comparison stimuli). That this effect depends on the similarity of retention interval (RI) and intertrial interval (ITI) houselight illumination conditions has been taken as evidence that pigeons judge duration relative to a temporal background.

Animal Learning & Behavior, 1990

A discriminal distance analysis procedure similar to that used by Roitblat (1980) was employed to test the hypotheses that animals either retrospectively (Spetch & Wilkie, 1983) or prospectively (Kraemer, Mazmanian, & Roberts, 1985) encode durations of events. Pigeons were required to discriminate 2-, 8-, and lO•sec presentations of light. Choices of red, orange, and green keys were correct after 2, 8, and 10 sec, respectively. The key elements in this design were (1) that some samples (8 and 10 sec) and some choice stimuli (red and orange) were more difficult to discriminate than were others, and (2) that an easy sample discrimination (2 vs. 8 sec) was mapped onto a difficult choice discrimination (red vs. orange), and vice versa. An examination of raw error scores and calculated confusion indexes in three experiments supported the hypothesis that subjects retrospectively, rather than prospectively, encode event duration. This research was supported by the Natural Sciences and Engineering Research Council of Canada. Suzanne MacDonald provided helpful comments. Shayne Kardal and Kevin Lee assisted with the experiments.

Animal Learning & Behavior, 1996

In traditional theories of discrimination learning, interactions between the two stimuli involved in a simple discrimination (Sϩ, to which responses are reinforced and SϪ, to which responses are not reinforced) have been interpreted primarily in terms of their physical similarity to each other (see, e.g., Hearst, 1968; Logan, 1966; Spence, 1937). For example, if a discrimination involves two very similar stimuli, the generalization of excitation resulting from reinforced responding to the Sϩ may generalize to the SϪ, making it very difficult for an organism to inhibit responding to the SϪ. Furthermore, what interaction does occur between the Sϩ and SϪ in a discrimination has been interpreted independently of the temporal relation between the two stimuli (i.e., whether they are presented simultaneously or successively). Recently, it has been suggested that during simultaneous discrimination training, some of the excitation or response strength acquired by the Sϩ transfers to the SϪ, independent of the physical similarity between the Sϩ and SϪ (Fersen, Wynne, Delius, & Staddon, 1991). This theory of transferred response strength, known as value transfer theory, has received empirical support (

Journal of the Experimental Analysis of Behavior, 2003

Two experiments examined pigeons' discrimination of directional movement using pictorial images shown on computer monitors. Stimuli consisted of the movement of a bird against a stationary background or the movement of the background behind a stationary bird. In Experiment 1, pigeons were trained to discriminate either leftward or rightward motion of either the bird or the background from stationary frames drawn from the same movies. The background-discrimination group acquired the discrimination faster than the bird-discrimination group. In Experiment 2, transfer of the discrimination from the task of Experiment 1 to a discrimination between motion directions was examined. Most of the pigeons learned this discrimination rapidly, whereas in a pilot study in which direction discrimination was trained without previous static/movement discrimination, learning was poor. It appears that an experimental history of movement against stationary discrimination promoted the pigeons' learning of the directional motion discrimination.

1992

Pigeons trained on cyclic-interval schedules adjust their postfood pause from interval to interval within each experimental session. But on regular fixed-interval schedules, many sessions at a given parameter value are usually necessary before the typical fixed-interval "scallop" appears. In the first case, temporal control appears to act from one interfood interval to the next; in the second, it appears to act over hundreds of interfood intervals. The present experiments look at the intermediate case: daily variation in schedule parameters. In Experiments 1 and 2 we show that pauses proportional to interfood interval develop on short-valued response-initiated-delay schedules when parameters are changed daily, that additional experience under this regimen leads to little further improvement, and that pauses usually change as soon as the schedule parameter is changed. Experiment 3 demonstrates identical waiting behavior on fixed-interval and response-initiated-delay schedules when the food delays are short (<20 s) and conditions are changed daily. In Experiment 4 we show that daily intercalation prevents temporal control when interfood intervals are longer (25 to 60 s). The results of Experiment 5 suggest that downshifts in interfood interval produce more rapid waiting-time adjustments than upshifts. These and other results suggest that the effects of short interfood intervals seem to be more persistent than those of long intervals. Key words: linear waiting, timing, fixed-interval schedules, response-initiated delay schedules, key peck, pigeons One of the most reliable aspects of performance on any reinforcement schedule is the postreinforcement pausing observed when reinforcers are delivered at regular time intervals. Independent of any response-reinforcer contingency, birds and mammals (including humans, under some conditions) learn to postpone food-related responses after each food delivery for a time proportional to the typical interfood interval (temporal control: Chung &

Learning and Motivation, 2008

Behavioural Processes, 2006

In Experiment 1, pigeons were trained to discriminate between sequences of two and four light flashes (illumination of the feeder). Retention functions obtained with dark delays exhibited a choose-many bias at a 1-s delay and a choose-few bias at delays of 4 and 8 s. Retention functions obtained with illuminated delays only displayed a slight choose-few bias. In Experiment 2, additional birds were trained with the same sample sequences. However, the intertrial interval was illuminated by the houselight for Group Light, and it was dark for Group Dark. The acquisition data suggested that multiple temporal features of the light flash sequences controlled choice responding. For both groups, the retention functions were similar to those obtained in Experiment 1. In Experiment 3, baseline training with a 1-s dark delay eliminated the choose-many bias, but a significant choose-few bias at extended dark delays was still observed. Pigeons discriminate light flash sequences by relying on temporal properties of the sequence rather than using an event switch to count flashes. The biased-forgetting effects obtained in these studies appear to be primarily due to confusion between the delay interval and the gap between light flashes.