Successive two-item same-different discrimination and concept learning by pigeons

Abstract

Four pigeons were trained in a successive same/different procedure involving the alternation of two stimuli per trial. Using a go/no-go procedure, two different or two identical color photographs were alternated, with a brief, dark, inter-stimulus interval, on a computer screen for 20 s. Pigeons learned to discriminate between same (S+) and different (D−) sequences with moderate to large contrasts between successive pictures. Analyses of pecking behavior within single trials revealed this discrimination emerged at the earliest possible point in the sequence (i.e. by the presentation of the second item). Pigeons transferred to novel color and gray-scale pictures, and showed savings in tests with novel video stimuli. These results suggest that same/different discrimination and concept formation can be acquired with successively presented pairs of stimuli by pigeons. When combined with results using simultaneous same/different presentations, these findings further support a qualitative similarity among birds and primates in their capacity to judge certain types of stimulus relations.

Two-itemsame-different concept learning in pigeons

“…In addition to learning a single, broadly applied rule, we have consistently found that pigeons can transfer this solution to novel exemplars from both within (Cook et al, 1995; and outside (Cook et al, 1999) the range of stimuli experienced during training. Recently, we found that they can also learn and transfer this behavior when trained and tested with successively presented photographic and video stimuli (Cook et al, 2003). As a whole, these results seem most consistent with the hypothesis that pigeons can detect, recognize, and abstract S/D visual relations in a variety of different test procedures.…”

“…This suggests that their problem may have been more attentional than conceptual in nature. Interestingly, in Cook et al's (2003) tests with a successive two-item procedure, the pigeons showed more difficulty in learning and transferring S/D discriminations with grayscale pictures than with fully colored versions of the same pictures. As such, shape differences not only may be perceptually more difficult for pigeons to detect, but also may be harder to conceptualize.…”

“…For instance, we have found that pigeons are capable of learning and applying an S/D concept across a wide variety of simultaneously presented visual items (Cook, 2002a(Cook, , 2002bCook, Cavoto, & Cavoto, 1995;Cook, Katz, & Cavoto, 1997;Cook, Katz, & Kelly, 1999;Cook & Wixted, 1997) and successively presented items (Cook, Kelly, & Katz, 2003). In these studies, pigeons have been shown to learn an S/D classification with up to five different multidimensional classes, ranging from smaller, densely packed textural elements (i.e., items) to more sparse arrays of geometrics, objects, and photographs (Cook, 2002a;Cook et al, 1999; examples of these different stimulus classes can be seen in the articles and on line at www.pigeon.psy.tufts.edu).…”

Generalized auditory same-different discrimination by pigeons.

“…Within the visual domain, birds have been shown to have the propensity of being controlled by both absolute and relational factors (Cook, Kelly, & Katz, 2003;Cook, Levison, Gillett, & Blaisdell, 2005;Wasserman, Frank, & Young, 2002). The same appears true for the auditory modality.…”

“…The pigeons consistently needed several auditory presentations, approximately 3 to 5, to consistently exhibit stimulus control within a sequence. We have previously found using successive visual presentations of color pictures clear evidence that S/D discrimination emerged after only the minimal number of two presentations (Cook, Kelly, & Katz, 2003). Another difference between the modalities was that we needed an asymmetrical learning procedure for the auditory stimuli that we have not had to employ in our visual studies.…”