ERRORLESS LEARNING OF A CONDITIONAL TEMPORAL DISCRIMINATION

Animal Cognition, 2020

Delaying reinforcement typically has been thought to retard the rate of acquisition of an association, but there is evidence that it may facilitate acquisition of some difficult simultaneous discriminations. After describing several cases in which delaying reinforcement can facilitate acquisition, we suggest that under conditions in which the magnitude of reinforcement is difficult to discriminate, the introduction of a delay between choice and reinforcement can facilitate the discrimination. In the present experiment, we tested the hypothesis that the discrimination between one pellet of food for choice of one alternative and two pellets of food for choice of another may be a difficult discrimination when choice consists of a single peck. If a 10-s delay occurs between choice and reinforcement, however, the discrimination is significantly easier. It is suggested that when discrimination between the outcomes of a choice is difficult and impulsive choice leads to immediate reinforcement, acquisition may be retarded. Under these conditions, the introduction of a brief delay may facilitate acquisition.

Psychonomic Bulletin & Review, 1998

In conditional discriminations, when samples differ only in duration, pigeons typically show a choose-short effect (i.e., 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 (IT!) houselight illumination conditions has been taken as evidence that pigeons judge duration relative to a temporal background. In the present experiment, pigeons trained with duration samples and with the ITI either illuminated or not showed a choose-short bias only when the RI illumination on test trials was the same as the ITI illumination had been in training. The results support the hypothesis that the choose-short effect results from the pigeons' confusion between the ITI and the RI. Pigeons can acquire a conditional discrimination (matching to sample) when the only conditional cue is the differential duration ofan otherwise identical stimulus. A task of this type might involve, for example, reinforcement of a red-comparison choice after a lO-sec white-keylight (long) sample and reinforcement of a green-comparison choice after a 2-sec white-keylight (short) sample. When trained on such a conditional discrimination, pigeons show divergent retention functions when delays are imposed between the samples and the comparison stimuli. That is, as the retention interval (RI) is increased, choice accuracy declines sharply on long-sample trials but remains high on short-sample trials. This counterintuitive finding has been attributed to the subjective shortening of events over time (

Journal of the Experimental Analysis of Behavior, 1977

Four pigeons had discrimination training that required the choice of a left side-key after completing a fixed-ratio 10 on the center key, and a right side-key choice after fixed-ratio 20. Correct choices were reinforced on various fixed-interval, fixed-ratio, random-interval, and random-ratio schedules. When performance was examined across successive 15-second intervals (fixed-interval and fixed-ratio schedules) accuracy was high in the first 15-second interval, decreased in one or several of the next 15-second intervals, and then increased again as reinforcement was approached. When perforlniance was examined across correct trials on fixed-interval and fixed-ratio schedules, accuracy was lowest immediately after reinforcement, followed by a systematic increase in accuracy as the number of correct choices increased. These patterns were due primarily to errors on fixed-ratio 20 trials. Systematic accuracy patterns did not occur on random-interval or random-ratio schedules. The results indicate that when choice patterns differed on fixed-interval and fixed-ratio schedLules, the differences were due to the method of data analysis.

Journal of the experimental analysis of …, 2008

Journal of Experimental Psychology: Animal Behavior Processes, 1984

Pigeons' key pecks turned off a key light, which also went off independently of their pecks. The pigeons were able to correctly discriminate the cause of the stimulus change, although their attributions were strongly affected by the amount and the delay of reward given for correct responses. Their discrimination was based on the asynchrony between a response and the change in the key light. A simple detection model that combined detectability and motivational factors provided a good description of the data. It was shown that the discriminative criteria did not change with changes in distribution of noise events in an optimal fashion and that the pigeons therefore were not "ideal detectors." In the final experiment, the pigeons were asked to discriminate the cause of a key light change, of a hopper illumination, and of a feeding. Performance decreased with each condition and with the duration of the last two events. It was noted that the memory trace for a stimulus change decays at the same rate as the primary reinforcement gradient but that it decays faster when the delay is filled with an event such as reinforcement. The possibility that the effects of reinforcement may be blocked by reinforcement is briefly discussed.

Psychonomic bulletin & review, 2004

Clement, Feltus, Kaiser, and Zentall (2000) reported that pigeons prefer discriminative stimuli that require greater effort (more pecks) to obtain over those that require less effort. In the present experiment, we examined two variables associated with this phenomenon. First, we asked whether delay of reinforcement, presumably a relatively aversive event similar to effort, would produce similar effects. Second, we asked whether the stimulus preference produced by a prior relatively aversive event depends on its anticipation. Anticipation of delay was accomplished by signaling its occurrence. Results indicated that delays can produce preferences similar to those produced by increased effort, but only if the delays are signaled.

Journal of the Experimental Analysis of Behavior, 1986

Six pigeons were trained to peck a red side key when the brighter of two white lights (S,) had been presented on the center key, and to peck a green side key when the dimmer of two white lights (S2) had been presented on the center key. Equal frequencies of reinforcers were provided for the two types of correct choice. Incorrect choices, red side-key pecks following S2 presentations and green sidekey pecks following S, presentations, resulted in blackout. With 0-s delay between choice and reinforcement, the delay between sample presentation and choice was varied from 0 to 20 s. Then, with 0-s delay between sample presentation and choice, the delay between choice and reinforcement was varied from 0 to 20 s. Both types of delay resulted in decreased discriminability (defined in terms of a signal-detection analysis) of the center-key stimuli, but delayed choice had more effect on discriminability than did delayed reinforcement. These data are consistent with the view that the two kinds of delay operate differently. The effect of a sample-choice delay may result from a degradation of the conditional discriminative stimuli during the delay; the effect of a choice-reinforcer delay may result from a decrement in control by differential reinforcement.

Journal of Experimental Psychology: Animal Behavior Processes, 1998

In 2 experiments, pigeons were trained on, and then transferred to, delayed simple discriminations in which the initial stimuli signalled reinforcement versus extinction following a retention interval. Experiment 1 showed that discriminative responding on the retention test transferred to novel test stimuli that had appeared in another delayed simple discrimination but not to stimuli having the same reinforcement history off-baseline. By contrast, Experiment 2 showed that performances transferred to novel initial stimuli whether they had been trained on-baseline or off-baseline. These results suggest that the test stimuli in delayed simple discriminations acquire control over responding only in the memory task itself. On the other hand, control by the initial stimuli, if coded as outcome expectancies, does not require such task-specific training. Comparing performances across different delayed discriminations has been a popular way to identify what animals remember during the retention interval of a working memory task. This comparison has been frequently driven by the belief that animals not only code the physical attributes of stimuli appearing prior to the retention interval (retrospective coding) but also anticipate events occurring with predictable regularity after the retention interval (prospective coding;

Journal of the Experimental Analysis of Behavior, 1976

Four pigeons in the line-positive group were trained with a vertical line on a green background that signalled intermittent reinforcement while a plain green field signalled extinction. Four pigeons in the line-negative group were trained with the opposite discrimination. Response to a control key terminated any trial and initiated the next trial. The birds also used the control key during generalization tests to control the durations of trials in which various line orientations were presented. These durations were summed to provide generalization gradients of stimulus duration that were positive or negative in accordance with the trained discriminations. In Experiment 2, birds from the line-positive group were tested with a procedure in which the control key was not available on some trials. This provided an independent assessment of response rates to the test stimuli. These rates were used to predict the stimulus durations obtained when the control key was available. The findings supported a general model for the prediction of response distributions among concurrent stimuli from rates observed with single stimuli.

Models of interval timing typically include a response threshold to account for temporal production. The present study sought to evaluate the dependent concurrent fixed-interval fixed-interval schedule of reinforcement as a tool for selectively isolating the response threshold in rats, pigeons, and humans. In this task, reinforcement is available either at one location after a short delay or at another location at a longer delay. Because the reinforced location is not signaled, subjects normally respond on the first location and, if reinforcement is not delivered, then switch to the second location. The latency to switch between locations served as the primary dependent measure. After training rats, pigeons, and humans with equal reinforcement magnitudes in the short and long delays, the magnitude of reinforcement was increased threefold on the long-delay location. Consistent with model predictions, this biasing procedure decreased estimates of the response threshold of rats and pigeons, but also reduced temporal control in these species and increased response-threshold estimates in humans. Human and pigeon performance also suggested a magnitude-induced increase in the speed of the internal clock. Collectively, these results suggest that differences in reinforcement magnitude between response alternatives appear to modulate the response threshold, but not selectively, and may provide guidance for better isolating response threshold effects in humans.