Transitive and anti-transitive emergent relations in pigeons: support for a theory of stimulus-class formation

Abstract

Stimulus class formation is inferred when conditional discrimination training yields new (emergent) conditional relations between the training stimuli. The present experiments demonstrated two such relations in pigeons after successive matching-to-sample training. Experiment 1 showed that transitivity (AC matching) emerged after training on AB and BC arbitrary matching plus BB identity matching: pigeons responded relatively more to the comparisons on AC test trials in which both the A samples and C comparisons were elements of reinforced arbitrary baseline relations involving the same nominal B stimulus. Experiment 2 showed the opposite effect ("anti-transitivity") after training on the same arbitrary relations but with BB oddity instead: pigeons responded relatively more to the comparisons on AC test trials in which the A sample was an element of a reinforced baseline relation and the C comparison was an element of a non-reinforced baseline relation, or vice versa. Experiment 2 also showed that AB and BC training alone generally does not yield an emergent effect. These findings extend the range of emergent phenomena observed in non-human animals and are consistent with predictions from Urcuioli's (2008) theory of pigeons' stimulus class formation. This article is part of a Special Issue entitled: Tribute to Tom Zentall.

Keywords: Anti-transitivity; Emergent relations; Pigeons; Stimulus classes; Successive matching; Transitivity.

Figure 1

The six stimulus classes hypothesized to result from arbitrary (AB and BC) form identity (BB) successive matching training in Experiment 1. Letters denote the nominal stimuli (R = red, G = green, B = blue, W = white, T = triangle, H = horizontal) and numbers denote ordinal position in a trial (1 = first (sample), 2 = second (comparison)).

Figure 2

The six stimulus classes shown in Figure 1 rearranged to show common class elements (ellipses). Letters denote the nominal stimuli (R = red, G = green, B = blue, W = white, T = triangle, H = horizontal) and numbers denote ordinal position in a trial (1 = first (sample), 2 = second (comparison)).

Figure 3

The two 4-member stimulus classes hypothesized to result from merging classes that contain common elements (cf. Figure 2). Letters denote the nominal stimuli (R = red, G = green, B = blue, W = white, T = triangle, H = horizontal) and numbers denote ordinal position in matching trial (1 = first (sample), 2 = second (comparison)). Arrows indicate predicted emergent transitive relations.

Figure 4

Comparison response rates in pecks/s (± 1 SEM) for the pigeons in Experiment 1 on arbitrary matching (AB) baseline trials (open circles) and the non-reinforced AC transitivity probe trials (filled circles) averaged over the eight test sessions. Positive = reinforced baseline trials and probe trials consisting of samples from reinforced AB baseline relations and comparisons from reinforced BC baseline relations. Negative = non-reinforced baseline trials and probe trials consisting of samples from reinforced AB baseline relations and comparisons from non-reinforced BC baseline relations or vice versa.

Figure 5

The six stimulus classes hypothesized to result from arbitrary (AB and BC) form oddity (BB) successive matching training in Experiment 2. Letters denote the nominal stimuli (R = red, G = green, B = blue, W = white, T = triangle, H = horizontal) and numbers denote ordinal position in a trial (1 = first (sample), 2 = second (comparison)).

Figure 6

The six stimulus classes shown in Figure 6 rearranged to show common class elements (ellipses). Letters denote the nominal stimuli (R = red, G = green, B = blue, W = white, T = triangle, H = horizontal) and numbers denote ordinal position in a trial (1 = first (sample), 2 = second (comparison)).

Figure 7

The two 4-member stimulus classes hypothesized to result from merging classes that contain common elements (cf. Figure 3). Letters denote the nominal stimuli (R = red, G = green, B = blue, W = white, T = triangle, H = horizontal) and numbers denote ordinal position in matching trial (1 = first (sample), 2 = second (comparison)). Arrows indicate predicted emergent transitive relations.

Figure 8

Comparison response rates in pecks/s (± 1 SEM) for pigeons in the anti-transitivity (AT) group of Experiment 2 on arbitrary matching (AB) baseline trials (open circles) and the non-reinforced AC probe trials (filled circles) averaged over the eight test sessions. Positive = reinforced baseline trials and probe trials consisting of samples from reinforced AB baseline relations and comparisons from reinforced BC baseline relations. Negative = non-reinforced baseline trials and probe trials consisting of samples from reinforced AB baseline relations and comparisons from non-reinforced BC baseline relations or vice versa.

Figure 9

Comparison response rates in pecks/s (± 1 SEM) for the pigeons in the control group of Experiment 2 on arbitrary matching (AB) baseline trials (open circles) and the non-reinforced AC probe trials (filled circles) averaged over the eight test sessions. Positive = reinforced baseline trials and probe trials consisting of samples from reinforced AB baseline relations and comparisons from reinforced BC baseline relations. Negative = non-reinforced baseline trials and probe trials consisting of samples from reinforced AB baseline relations and comparisons from non-reinforced BC baseline relations or vice versa.