Value transfer in a simultaneous discrimination by pigeons: The value of the S+ is not specific to the simultaneous discrimination context

Abstract

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.

Alternative accounts are preferable to value transfer theory: Commentary on Dorrance, Kaiser, and Zentall (1998)

“…Analogous arguments can be applied to the procedures used by Dorrance et al (1998). All birds within these experiments were trained to a 90% correct criterion on the two discriminations: Thus the animals in each experiment who got most differential training were those that needed it most to learn to the criterion; as such they would not show enhanced preference as a result of this training.…”

“…

Dorrance, Kaiser, and Zentall (1998) Kaiser, and Zentall (1998) have reported a series of experiments on simultaneous discrimination learning by pigeons in which the value ofthe positive discriminative stimulus (S+) was varied outside the context of the simultaneous discrimination. Following concurrent training on two such discriminations, the relative.value of the two S-stimuli was assessed by means of a choice procedure.

…”

“…Interspersed with these trials are single-stimulus trials on which stimulus A or C is presented alone, with responding to stimulus A reinforced with a greater probability than that for responding to stimulus C. Following this training, the pigeons were presented with a choice between Band D. In each of the four experiments, the pigeons showed a preference for stimulus B. Dorrance et al (1998) interpret these results in terms of value transfer theory (VTT), in which it is assumed that some ofthe value ofthe S+ in a simultaneous discrimination transfers to the S-. Thus, according to VTT, choice responding would be more likely to B than to D in the simplified design shown in Table I, because more value would transfer to B from A, which is reinforced during the single-stimulus trials, than would transfer from C to D. The authors compare this account with an occasion setting account, which fails, as the authors note, to predict the observed preferences in any of the four experiments.…”

Simultaneous discrimination learning: Stimulus interactions

“…In four experiments, Dorrance, Kaiser, and Zentall (1998) found support for value transfer theory. In each case, the relative average value of the S1 (presented by itself, as well as in the context of the S ) predicted the preference for the S on test trials (see Table 6).…”

“…Is it possible that the inclusion of singlestimulus trials among discrimination trials will generally convert the relation between S1 and S from value transfer to contrast-even in a positive value transfer design? Clearly, single-stimulus trials are not sufficient to produce contrast, because Dorrance et al (1998) found value transfer when single-stimulus presentations of the S1 stimuli were included in training. However, in each of the experiments reported by Dorrance et al, the value of at least one of the S1 stimuli changed when it was presented as a single stimulus.…”