Issues in the Comparative Cognition of Abstract-Concept Learning

Abstract

-concept learning, including same/different and matching-to-sample concept learning, provides the basis for many other forms of "higher" cognition. The issue of which species can learn abstract concepts and the extent to which abstract-concept learning is expressed across species is discussed. Definitive answers to this issue are argued to depend on the subjects' learning strategy (e.g., a relational-learning strategy) and the particular procedures used to test for abstract-concept learning. Some critical procedures that we have identified are: How to present the items to-be-compared (e.g., in pairs), a high criterion for claiming abstract-concept learning (e.g., transfer performance equivalent to baseline performance), and systematic manipulation of the training set (e.g., increases in the number of rule exemplars when transfer is less than baseline performance). The research covered in this article on the recent advancements in abstract-concept learning show this basic ability in higher-order cognitive processing is common to many animal species and that "uniqueness" may be limited more to how quickly new abstract concepts are learned rather than to the ability itself.

Figure 1

An example of a different and same display each in a 3 × 2 array used in Cook, Katz, & Cavoto (1997).

Figure 2

Examples of multi-item displays used in Young & Wasserman (1997), ranging from a same (OD/16S) to different display (16D/0S). The labels represent how many items in the display were different and same. Note. From Figure 5, “Entropy detection by pigeons: Response to mixed visual displays after same-different discrimination training,” by M. E. Young and E. A. Wasserman, 1997, Journal of Experimental Psychology: Animal Behavior Processes, 23, p. 163. Copyright 1997 by the American Psychological Association. Adapted with permission.

Figure 3

Examples of a two-item same and different display used with capuchin monkeys, rhesus monkeys, and pigeons. The examples are proportional to the actual displays. The display sizes were smaller for pigeons to equate visual angle across species. Rhesus monkeys and pigeons were required to first make observing responses (touches or pecks) to the upper picture before they were presented simultaneously the two pictures and white rectangle permitting a choice (left panel). Capuchin monkeys were not required to make this initial observing response requirement (right panel). In either procedure, a touch or peck to the lower picture was correct on same trials and a touch or peck to the white rectangle was correct on different trials. After a choice response, displays were extinguished, correct choices rewarded, and a 15-s intertrial interval separated trials. Thus, except for the initial observing response, the sequence of events was identical across species. Note. From Figure 1, “Mechanisms of same/different abstract-concept learning by rhesus monkeys (Macaca mulatta),” by J. S. Katz, A. A. Wright, and J. Bachevalier, 2002, Journal of Experimental Psychology: Animal Behavior Processes, 28, p. 361. Copyright 2002 by the American Psychological Association. Adapted with permission.

Figure 4

The initial 8 training items used to train the three species in the S/D procedure. This 8-item set was used to construct the 64 training pairs (8 same and 56 different). These pairs were randomly selected during training. Note. From Figure 1, “Mechanisms of same/different abstract-concept learning by rhesus monkeys (Macaca mulatta),” by J. S. Katz, A. A. Wright, and J. Bachevalier, 2002, Journal of Experimental Psychology: Animal Behavior Processes, 28, p. 361. Copyright 2002 by the American Psychological Association. Adapted with permission.

Figure 5

Mean percentage correct for baseline and transfer at each set size for the three species in the S/D procedure. Error bars represent SEMs. Note. From Figure 3, “Same/different abstract-concept learning by pigeons,” by J. S. Katz and A. A. Wright, 2006, Journal of Experimental Psychology: Animal Behavior Processes, 32, p. 85. Copyright 2006 by the American Psychological Association. Adapted with permission

Figure 6

Mean percentage correct for baseline and transfer in the experimental and control groups of pigeons (left panel) and rhesus monkeys (right panel) at each set size or at equivalent points in training in the S/D procedure. Error bars represent SEMs. Note. From Figure 2, “Same/different abstract-concept learning by pigeons,” by J. S. Katz and A. A. Wright, 2006, Journal of Experimental Psychology: Animal Behavior Processes, 32, p. 84. From Figure 7, “Mechanisms of same/different abstract-concept learning by rhesus monkeys (Macaca mulatta),” by J. S. Katz, A. A. Wright, and J. Bachevalier, 2002, Journal of Experimental Psychology: Animal Behavior Processes, 28, p. 366. Copyrights 2006 and 2002 by the American Psychological Association. Adapted with permission.

Figure 7

An example of matching-to-sample displays used with pigeons. Pigeons were required to first make observing responses (pecks) to the sample (upper) cartoon before they were presented simultaneously the sample and two comparison cartoons (left panel). Some pigeons were not required to make this initial observing response requirement (right panel). In either procedure, a peck to the comparison cartoon that matches the sample cartoon was correct. After a choice response, correct choices were rewarded, and an intertrial interval separated trials. Thus, except for the initial observing response, the sequence of events was identical across procedures.

Figure 8

Mean percentage correct for trained displays (baseline) and novel-stimulus displays (transfer) at each set size for separate groups of pigeons in the MTS procedure. Error bars represent SEMs. Note. From Figure 7, “Concept learning by pigeons: Matching-to-sample with trial-unique video picture stimuli,” by A. A. Wright et al., 1988, Animal Learning & Behavior, 16, p. 443. Copyright 1988 by the Psychonomic Society. Adapted with permission.

Figure 9

Mean percentage correct for baseline and transfer at each set size for rhesus monkeys trained with ten sample observing response (FR10) or no sample observing response (FR0) in the S/D procedure. Error bars represent SEMs. Note. From Figure 6, “Abstract-concept learning and list-memory processing by capuchin and rhesus monkeys” by A. A. Wright, J. J. Rivera, J. S. Katz, and J. Bachevalier, 2003, Journal of Experimental Psychology: Animal Behavior Processes, 29, p. 191. Copyright 2003 by the American Psychological Association. Adapted with permission.

Figure 10

The twelve display configurations constructed from the three cartoon items (apple, duck, grapes) used in the MTS procedure. Pigeons were trained with either the top or bottom six displays. Notice that the role of each item in each of the two training sets is counterbalanced for sample frequency, correct comparison position, and incorrect comparison position. The six displays of the set not used in training were used to test for if-then rule learning. Note. From Figure 1, “Concept learning and learning strategies,” by A. A. Wright, 1997, Psychological Science, 8, p. 120. Copyright 1997 by Blackwell Publishing. Adapted with permission.

Figure 11

Mean percentage correct for trained, untrained, and novel-stimulus displays from Wright (1997). Error bars represent SEMs. Data are further divided by the number of responses required to the sample for each group. Untrained displays refer to tests of the six displays not used in training. Novel-stimulus displays refer to tests with trial-unique novel cartoon items not seen in training. The dotted line represents chance performance. Note. From Figure 2, “Concept learning and learning strategies,” by A. A. Wright, 1997, Psychological Science, 8, p. 121. Copyright 1997 by Blackwell Publishing. Adapted with permission.