Same-different texture discrimination and concept learning by pigeons.

Abstract

The acquisition and transfer of a "same-different" conditional discrimination using multidimensional visual texture stimuli was investigated in pigeons. Using a choice task, 4 pigeons were reinforced for discriminating different displays, created from aggregated differences in element color or shape, from uniform displays, in which all elements were identical. Discrimination of these 2 display types was readily acquired by the pigeons when they were required to locate and peck the contrasting target region of the different displays. The pigeons showed high levels of discrimination transfer to novel texture stimuli both during acquisition and in 2 subsequent transfer tests. The results suggest that pigeons may be able to learn a generalized same-different concept when promoted by the use of large numbers of multielement stimuli during training.Concepts are an essential part of human cognition, intelligence, and expression. With the growing interest in the cognitive abilities of nonhuman animals, a natural question is to what extent do animals use concepts in guiding their behavior (Herrnstein, 1990). Over the last 30 years, for instance, researchers have established abundant evidence for the formation and use of visually based object concepts by pigeons (Herrnstein & Loveland, 1964;Herrnstein, Loveland, & Cable, 1976;Wasserman, Kiedinger, & Bhatt, 1988). However, evidence for the use of more abstract concepts by pigeons, such as generalized "matching," "oddity," or "same-different" discriminations, has been far more difficult to obtain.Research on abstract concept learning in pigeons has for the most part focused on whether pigeons learn generalized matching or oddity rules in matching-to-sample and oddityfrom-sample discriminations. Although many studies have failed to find evidence of concept-based transfer in such conditional discriminations (Berryman, Cumming, Cohen,

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

“…The successful learning and transfer across sequences of successively presented visual stimuli helps to eliminate several alternative interpretations of our earlier S/D results (Cook et al, 1995(Cook et al, , 1999 collected using a simultaneous procedure. For instance, the results argue against concerns that our previous S/D results were due to the "generalized" detection of perceptual patterns or spatial anomalies within the mosaic of repeated elements in those displays.…”

“…Further, the pace of S/D learning with these different stimulus classes proceeds at the same rate, suggesting that the same common discrimination framework or decision criterion is applied across all of these distinct types (Cook, 2002b;. In addition to learning a single, broadly applied rule, we have consistently found the pigeons transfer this solution to novel exemplars from both within (Cook et al, 1995 and outside the range of stimuli experienced during training (Cook et al, 1999). This latter kind of transfer is important as the greater the range of novel conditions over which a discrimination can be applied, the more abstract a conceptual representation is required.…”

“…We found in analyzing where the pigeons pecked at the displays that they showed a strong tendency to peck at the outer portions of the left, right, and bottom edges of the displays (the bottom portion likely being attractive because of its proximity to the food hopper). If pigeons primarily process only what they peck at, then it is possible they never detected the contrasting objects in the center of the display, and thus preventing their discrimination (Cook et al, 1995;see Katz et al, 2002 for a similar argument with monkeys). A second possibility is that the pigeons did detect the figural changes between the stimuli, but that the proportion of change relative to their common background was not sufficient for the pigeons to consider it a "different" enough stimulus and respond accordingly.…”

“…After learning this discrimination, the degree to which this behavior transfers to novel situations having same and different relations is taken as evidence of concept formation. Using this choice task, it has been found that pigeons, parrots, rhesus monkeys, baboons, and chimpanzees are capable of learning and applying a S/D concept across a wide variety of simultaneously presented visual elements (Bovet and Vauclair, 2001;Cook, 2002a,b;Cook et al, 1995Cook et al, , 1999Cook and Wixted, 1997;Katz et al, 2002;Pepperberg, 1987;Thompson et al, 1997).…”

“…Mackintosh, 2000). For example, in texture-based S/D displays, discrimination could be based on detection of the presence or absence of a square border contrast between the target and distractor region (Cook et al, 1995). If true, then pigeons could successfully discriminate novel displays based on the detectable presence or absence of this simple perceptual feature and not on an abstract representation of its component relations.…”