Generalization of visual matching and delayed matching by a California sea lion (Zalophus californianus)

Abstract

Only a limited number of species have been found capable of generalized matching-to-sample (MTS) after exposure to relatively few training exemplars. We trained a juvenile, experimentally naive California sea lion (Zalophus californianus) in MTS, using a pair of three-dimensional objects as samples. Successful matehing to a criterion of 90% correct or better over 2 successive sessions was attained in 12 sessions (269 trials and 70 errors), Two subsequent "partial" transfer tests, in which each of the two training objects was paired with a novel test object, and four additional transfer tests, a11 with novel objects, were presented fo11owing training. An 80% performance criterion over 2 successive sessions was reached, or closely approximated, in from 2 to 4 transfer sessions for a11 transfer tests; errors to criterion tended to be reduced across the successive novel transfer tests and were as few as five during the final two tests; and performance on the first 48 trials of the last two novel transfers was not significantly different from a nearceiling level baseline performance measure. Neophobie responses of the sea lion to new objects precluded an unbiased evaluation of immediate (Trial 1) transfer. The sea Iion's short-term memory for sample objects was also measured. Matching performance was maintained at a level of 78% correct responses or better for delays through to 45 sec after removal of the sample object. At a 58-sec delay, the longest tested, performance declined to 69% correct responses. These retention levels are only somewhat below levels reported for dolphins and nonhuman primates tested on visual delayed MTS, but they are above levels typically reported for pigeon subjects.A fundamental issue in comparative cognition is the ability of animals to form broad, general concepts about the relationships among objects or other types of stimuli.Although this ability may be tested within many different paradigms (see Roitblat, 1987, for a review), tasks that direct the animal to detect and report on the identity relationship have been particularly useful. These include same/different tasks, in which the animal judges whether or not two items are identical (e.g., Wright, 1971), as well as matching-to-samp1e (MTS) tasks (e.g., D'Arnato, 1973). There are several forms of the MTS task (cf. D' Amato & Worsham, 1974;Herman & Thompson, 1982;Roitblat & Scopatz, 1983); in this paper, we will 37report on visual identity MTS. This task is typified by three steps: (1) the exposure, usually brief, of a sample stimulus, followed by the stimulus' removal; (2) the interposition of a delay period, ranging from 0 sec upwards; and (3) the exposure oftwo or more altematives, one of which physically matches the sample. The animal is rewarded for choosing the matehing alternative.To measure the development of a concept of identity, the experimenter presents new stimulus items after MTS training has been completed with a limited number of items; the experimenter then tests whether or not the subject can transfer the identity r...

Transfer of visual identity matching-to-sample in two california sea lions (zalophus californianus)

“…Transfer or generalization of a sameness concept has been reported in a variety of subjects, including pigeons (Wright, Cook, Rivera, Sands, & Delius, 1988;Zentall & Hogan, 1974), monkeys Wright et al, 1990), chimpanzees (Nissen et al, 1948;Oden, Thompson, & Premack, 1988), a sea lion (Pack, Herman, & Roitblat, 1991), and a dolphin (Herman, Hovancik, Gory, & Bradshaw, 1989). It has been argued that dolphins and chimpanzees (presumably because of their large brains) easily form concepts, while smallerbrained animals (pigeons) have much more difficulty in doing so.…”

“…It has been argued that dolphins and chimpanzees (presumably because of their large brains) easily form concepts, while smallerbrained animals (pigeons) have much more difficulty in doing so. Species intermediate in brain size (such as sea lions and monkeys) are thought to form concepts with more difficulty than dolphins and chimpanzees, but more easily than pigeons (Pack et al, 1991).…”

“…First, and probably most important, is the "exclusion" effect, which provides an explanation other than that of concept formation that is applicable to several studies reporting transfer of an identity rule in monkeys , pigeons (Holmes, 1979), a dolphin (Herman et al, 1989), and a sea lion (Pack et al, 1991). During testing, the correct and incorrect comparisons are often chosen such that the correct comparison is a novel stimulus and the incorrect comparison is familiar (i.e., previously trained).…”

“…In addition, novelty itself can affect test results if individual animals respond in unusual and disruptive ways to presentation of novel test stimuli (Holmes, 1979;Pack et al, 1991). In order to properly assess generalization, an experimenter needs to determine how the subject responds on the very first exposure to novel identity problems.…”

Sea Lions and Equivalence: Expanding Classes by Exclusion

“…In conditional discrimination procedures involving arbitrary or identity matching, California sea lions and harbor seals errorlessly matched novel visual samples and comparisons when the alternative was a member of an established stimulus pairing (Hanggi & Schusterman, 1995;D. Kastak & Schusterman, 1994;Pack, Herman, & Roitblat, 1991;Schusterman, Gisiner, Grimm, & Hanggi, 1993). Common chimpanzees trained to perform conditional discriminations also related novel samples to new comparisons in the contexts of language training or conditional discrimination procedures (see reviews in Cerutti & Rumbaugh, 1993;Tomonaga, 1993).…”