Pigeons were trained to match-to-sample with several new methodologies: a large number of stimuli, computer-drawn color picture stimuli, responses monitored by a computer touch screen, stimuli presented horizontally from the floor, and grain reinforcement delivered onto the picture stimuli. Following acquisition, matching-to-sample concept learning was assessed by transfer to novel stimuli on the first exposure to pairs of novel stimuli. One group (trial-unique), trained with 152 different pictures presented once daily, showed excellent transfer (80% correct). Transfer and baseline performances were equivalent, indicating that the matching-to-sample concept had been learned. A second group (2-stimulus), trained with only two different pictures, showed no evidence of transfer. These results are discussed in terms of the effect of numbers of exemplars on previous failures to find concept learning in pigeons, and the implications of the positive finding from this experiment on abstract concept learning and evolutionary cognitive development.Human cognitive behavior is characterized, in part, by our ability to abstract rules and form abstract concepts (Medin & Schaffer, 1978). Indeed, even our ability to effectively communicate with others depends upon this ability (Premack, 1978). One question that logically follows from discussions of human cognitive capabilities is: To what degree can animals form and learn concepts? Whether they can or not, bears upon one measure of how unique humans really are in the evolutionary hierarchy of cognitive abilities.The concepts, which are the focus of this article, are relational ones; they depend upon relations between pairs of items, for example, in situations in which subjects judge whether or not two items are identical (same) or nonidentical (different)-a same/different task-or ones in which they choose a comparison item to match a previously presented sample item-matching-to-sample. It is possible to learn a rule-based concept in these situations, so that any pair of items can be correctly judged. These relational concepts are to be contrasted to

Two rhesus monkeys were tested for octave generalization in 8 experiments by transposing 6-and 7-note musical passages by an octave and requiring same or different judgments. The monkeys showed no octave generalization to random-synthetic melodies, atonal melodies, or individual notes. They did show complete octave generalization to childhood songs (e.g., "Happy Birthday") and tonal melodies (from a tonality algorithm). Octave generalization was equally strong for 2-octave transpositions but not for 0.5or l.S-octave transpositions of childhood songs. These results combine to show that tonal melodies form musical gestalts for monkeys, as they do for humans, and retain their identity when transposed with whole octaves so that chroma (key) is preserved. This conclusion implicates similar transduction, storage, processing, and relational memory of musical passages in monkeys and humans and has implications for nature-nurture origins of music perception. Music is considered among cultures' highest achievements. Nevertheless, music from different cultures shares many characteristics. Among these common characteristics is that all music uses a limited number of possible notes. A limited number of possible notes helps to make songs memorable and reproducible. Other factors contribute to their memorability, reproducibility, and general appeal. Take, for example, the familiar tune "Happy Birthday." There is no doubt about its memorability. The first four notes readily identify it. Furthermore, different sets of four notes separated by whole octaves suffice equally well to identify "Happy Birthday." Preverbal infants as well as adults can identify a transposed melody as the same melody while at the same time recognizing that the notes are different, that is, different pitch heights (e.g.,

Three capuchin monkeys (Cebus apella) touched the lower of 2 pictures (same) or a white rectangle (different), increased same/different abstract-concept learning (52% to 87%) with set-size increases (8 to 128 pictures), and were better than 3 rhesus monkeys (Macaca mulatta). Three other rhesus that touched the top picture before choices learned similar to capuchins but were better at list-memory learning. Both species' serial position functions were similar in shape and changes with retention delays. Other species showed qualitatively similar shape changes but quantitatively different time-course changes. In abstract-concept learning, qualitative similarity was shown by complete concept learning, whereas a quantitative difference would have been a set-size slope difference. Qualitative similarity is discussed in relation to general-process versus modular cognitive accounts.

Recognition memory was tested for lists of 6 briefly (0.08 s) presented pictures at different interstimulus intervals (ISI) of 0.08, 1, and 4 s. Experiment 1 showed a 16% performance increase (ISI effect) for increasing ISI for travel slide but not kaleidoscope pictures. Experiment 2 showed that learning names for the kaleidoscope pictures then resulted in a substantial (20%) ISI effect, not attributable solely to the added exposure to the pictures. Experiment 3 required names, color evaluations, or blank stares during list-memory presentations. Interviews established that the most effective memory strategy was chaining the names together, followed by repeating the most current name, and in turn followed by reliance upon only the sensory experience. All groups in Experiments 2 and 3, independent of ISI effects, showed U-shaped serial position functions. Rehearsal is shown to be nonessential and cannot be the general cause of the primary effect of the serial position function.

Change detection is commonly used to assess capacity (number of objects) of human visual short-term memory (VSTM). Comparisons with the performance of non-human animals completing similar tasks have shown similarities and differences in object-based VSTM, which is only one aspect ("what") of memory. Another important aspect of memory, which has received less attention, is spatial short-term memory for "where" an object is in space. In this article, we show for the first time that a monkey and pigeons can be accurately trained to identify location changes, much as humans do, in change detection tasks similar to those used to test object capacity of VSTM. The subject's task was to identify (touch/peck) an item that changed location across a brief delay. Both the monkey and pigeons showed transfer to delays longer than the training delay, to greater and smaller distance changes than in training, and to novel colors. These results are the first to demonstrate location-change detection in any non-human species and encourage comparative investigations into the nature of spatial and visual short-term memory.