The 2-action method was used to examine whether imitative learning in Japanese quail (Coturnix japonica) depends on the motivational state of the observer quail at the time of observation of the demonstrated behavior. Two groups of observers were fed before observation (satiated groups), whereas 2 other groups of observers were deprived of food before observation (hungry groups). Quail were tested either immediately following observation or after a 30-min delay. Results indicated that quail in the hungry groups imitated, whereas those in the satiated groups did not, regardless of whether their test was immediate or delayed. The results suggest that observer quail may not learn (through observation) behavior that leads to a reinforcer for which they are unmotivated at the time of test. In addition, the results show that quail are able to delay the performance of a response acquired through observation (i.e., they show deferred imitation).

In the present experiments, the 2-action method was used to determine whether pigeons could learn to imitate a conditional discrimination. Demonstrator pigeons (Columba livia) stepped on a treadle in the presence of 1 light and pecked at the treadle in the presence of another light. Demonstration did not seem to affect acquisition of the conditional discrimination (Experiment 1) but did facilitate its reversal of the conditional discrimination (Experiments 2 and 3). The results suggest that pigeons are not only able to learn a specific behavior by observing another pigeon, but they can also learn under which circumstances to perform that behavior. The results have implications for proposed mechanisms of imitation in animals.

During simultaneous discrimination training, there is evidence that some of the value of the S+ transfers to the S-. When the value ofthe S+ is altered outside the context of the simultaneous discrimination, two very different predictions are made concerning its effect on its S-, depending on whether one views the S+ as an occasion setter or as a stimulus capable of transferring value. In four experiments, pigeons were trained with two similar simultaneous discriminations, A+B-and C+D-, and two singlestimulus trial types, A and C, (in which A always had greater nominal value than C). According to value transfer theory, on test trials, B should always be preferred over D, because B and D should be affected by the net values of Aand C, respectively. According to an occasion setting account, however, D should be preferred over B because the presence of D signals a higher probability of reinforcement for responding to C than when C is alone, and/or the presence of B signals a lower probability of reinforcement for responding to A than when A is alone. In all four experiments, the pigeons preferred B over D, a result consistent with value transfer theory. Thus, an S-can acquire value from an S+ even when that value is conditioned in a "context" different from that of the simultaneous discrimination.

Pigeons trained on a conditional event-duration discrimination typically "choose short" when retention intervals are inserted between samples and comparisons.In two experiments, we tested the hypothesis that this effect results from ambiguity produced by the similarity of the novel retention intervals and the familiar intertrial interval by training pigeons with retention intervals from the outset and, for one group, in addition, making retention intervals distinctive from the intertrial intervals. In Experiment 1,when the retention intervals (0-4 sec) were not distinctive from the intertrial intervals, the pigeons did not show a clear choose-short effect even when extended retention intervals (8 sec) were introduced. When the retention intervals were distinctive, the pigeons showed a choose-long effect (they appeared to time through the retention interval), but it was relatively weak until the retention intervals were extended to 8 sec. In Experiment 2, when pigeons were discouraged from timing through the retention intervals by making the intertrial intervals and retention intervals salient distinct events and using long (up to 16-sec) retention intervals in training, parallel retention functions were found. It appears that when ambiguity is removed, forgetting by pigeons does not occur by the process of subjective shortening. These experiments suggest that the accurate interpretation of results of animal memory research using differential-duration samples must consider the novelty of the retention intervals on test trials as well as their similarity to other trial events.When pigeons are trained on a conditional discrimination in which the duration ofthe sample serves as the conditional stimulus (a short sample indicates that one of the comparisons is correct, and a long sample indicates that the other comparison is correct), the slope ofthe retention function with increasing delays depends on whether the sample is the longer or the shorter duration. Specifically, as retention intervals increase, matching accuracy on the short-sample trials typically remains high, but matching accuracy on the long-sample trials declines rapidly--often falling below chance at longer retention intervals (e.g., Spetch & Wilkie, 1982). These results have been interpreted as evidence of the subjective shortening of event duration with increasing retention intervals. That is, as the retention interval increases, memory for the sample duration shortens, such that, after longer retention intervals, memory for the long sample is actually more similar to that of the short sample at no delay (see Staddon & Higa, 1999, for a formal version of this model).Surprisingly, however, there is evidence, that this "choose-short" effect can be eliminated by merely illuminating the houselight during the intertrial interval. Under these conditions, the pigeons show parallel reten- tion functions (Spetch & Rusak, 1992). To account for this finding, Spetch and Rusak proposed that the pigeons evaluate the durations of the samples relative to the tempor...

In two experiments involving presentJabsent sample matching, we tested whether the visual stimuli or differential sample behavior served as the basis for comparison choice. In both experiments, one group (FRlDRO) was required to peck the present sample and to refrain from pecking the absent sample (as typically occurs with fixed duration present/absent samples), and the other group (FRlFR) was required to peck both sampies. In Experiment 1, the sampies were a black dot on a white field (present) and the white field alone (absent). In Experiment 2, the sampies were a yellow hue (present) and a dark response key (absent). In both experiments, divergent retention functions were found only for the FRIDRO group. These results suggest that, in nonhedonic presentJabsent sample matching, it is the behavior directed toward the present sample, rather than the visual stimulus itself, that serves as the basis for comparison choice.