Roger K. R. Thompson

Language-Naive Chimpanzees (Pan troglodytes) Judge Relations Between Relations in a Conceptual Matching-to-Sample Task

Three chimpanzees with a history of conditional and numeric token training spontaneously matched relations between relations under conditions of nondifferential reinforcement. Heretofore, this conceptual ability was demonstrated only in language-trained chimpanzees. The performance levels of the language-naive animals in this study, however, were equivalent to those of a 4th animal--Sarah--whose history included language training and analogical problem solving. There was no evidence that associative factors mediated successful performance in any of the animals. Prior claims of a profound disparity between language-trained and language-naive chimpanzees apparently can be attributed to prior experience with arbitrary tokens consistently associated with abstract relations and not language per se.

Categorical Perception and Conceptual Judgments by Nonhuman Primates: The Paleological Monkey and the Analogical Ape

Abstract Studies of the conceptual abilities of nonhuman primates demonstrate the substantial range of these abilities as well as their limitations. Such abilities range from categorization on the basis of shared physical attributes, associative relations and functions to abstract concepts as reflected in analogical reasoning about relations between relations. The pattern of results from these studies point to a fundamental distinction between monkeys and apes in both their implicit and explicit conceptual capacities. Monkeys, but not apes, might be best regarded as “paleo-logicans” in the sense that they form common class concepts of identity on the basis of identical predicates (i.e., shared features). The discrimination of presumably more abstract relations commonly involves relatively simple procedural strategies mediated by associative processes likely shared by all mammals. There is no evidence that monkeys can perceive, let alone judge, relations-between-relations. This analogical conceptual capacity is found only in chimpanzees and humans. Interestingly, the “analogical ape,” like the child, can make its analogical knowledge explicit only if it is first provided with a symbol system by which propositional representations can be encoded and manipulated

Spontaneous transfer of matching by infant chimpanzees (Pan troglodytes).

Four infant chimpanzees learned a matching-to-sample task when only two training stimuli were used. They then spontaneously transferred the matching concept to novel items, including three-dimensional objects and fabric swatches, without any experimenter-provided differential feedback. These results support the view that the matching concept is broadly construed by chimpanzees from the beginning and does not depend upon explicit training.

Retrospective and Prospective Processing in Animal Working Memory

Publisher Summary This chapter describes current research in the area of “short term,” or, “working memory” in animals. The memory processes provide a model for the actual functioning of working memory in the “real lives” of many animals, and learn about temporal contingencies in their environment and make appropriate, adaptive response decisions. When the same initial stimuli are used and the memory functions differ, they indicate different memory processes or prospective memory processing with differing degrees of stimulus specificity. The direct procedures involve (1) cues presented in advance of alternative test conditions or trial outcomes, with the attendant use of the probe procedure; (2) changes in the number of initial stimuli or differences among them; and (3) differential opportunities to practice remembering.

Tonic immobility in Japanese quail can reduce the probability of sustained attack by cats

In a two-choice experiment, cats (Felis domesticus) chose an active quail (Coturnix coturnix japonica) more often than a quail in tonic immobility (TI). In a second experiment, cats were individually presented with two active quail in an open field. Holding and biting by the cat, particularly about the neck, was necessary for inducing TI in a bird. Overall, the total time spent by a cat in stalking, attacking, and handling a bird was inversely related to the total time spent in TI by the bird. These results support the hypothesis that TI is a terminal defense mechanism elicited by predator contact. TI apparently eliminates the movement stimuli that sustain further attack.

Underwater frequency discrimination in the bottlenosed dolphin (1–140 kHz) and the human (1–8 kHz)

Frequency difference limens (DLs) were obtained for frequencies (F) from 1 to 140 kHz for the bottlenosed dolphin, Tursiops truncatus (Montagu), and from 1 to 8 kHz for two human subjects tested underwater. Discriminations were required between constant‐frequency (pure‐tone) signals and frequency‐modulated signals, using a successive discrimination procedure. Relative DLs (DL/F) for the dolphin generally ranged from 0.002 to 0.004 between 2 and 53 kHz, and never exceeded 0.008 through to 130 kHz; at 1 and 140 kHz, relative DLs increased to 0.014. No responses were obtainable at 150 kHz. These findings demonstrate excellent frequency discrimination throughout the audible spectrum (above 1 kHz) of Tursiops and support electrophysiological evidence of highly sensitive frequency detection mechanisms. Results for the humans showed smaller DLs than the dolphin at 1 kHz, approximately equal DLs at 2 kHz, and progressively larger DLs at 4 and 8 kHz. The human underwater thresholds were generally consistent with t...

A profound disparity revisited : Perception and judgment of abstract identity relations by chimpanzees, human infants, and monkeys

We review the evidence for three important disparities involving the perception and judgment of identity relations by human and nonhuman primates. First, only humans beyond infancy and adult chimpanzees (Pan troglodytes) with a history of language or token training can explicitly judge relations (same or different) between relations (identity and nonidentity) in a matching-to-sample (MTS) task. Second, both human and chimpanzee infants perceive relational similarity as measured in preference-for-novelty tasks. The human and chimpanzee infants, however, do not express this tacit knowledge in judgmental tasks like relational MTS. Third, unlike the human and chimpanzee infants, adult rhesus monkeys (Macaca mulatta) tested with the same preference-for-novelty tasks do not perceive abstract relational similarities and differences despite their sensitivity to physical identity.

Auditory delayed discriminations by the dolphin: Nonequivalence with delayed-matching performance

Working memory in a bottlenosed dolphin was tested in both indirect and direct auditory delayed-discrimination tasks in which a correct spatial response was conditional upon the nature of a preceding sound. In the indirect task, either one of two possible sounds was briefly presented. After a prescribed delay, the dolphin was cued to go either to a left-hand or right-hand paddle pair. Responses to the outer paddle of a pair were rewarded following sound A, and responses to the inner paddle of a pair were rewarded after sound B. In the direct delayed-discrimination task, only one paddle pair was used in each session. In both tasks, the delay interval between the discriminative sound stimulus and the opportunity for a spatial response was progressively increased over sessions until the animal failed to meet a specified performance criterion or self-terminated a session. Delay limits of about 30 and 60 sec were obtained in the indirect and direct tasks, respectively. The increase in delay limit in the latter task was attributable to the use of an overt mediational response during the longer delays. In both cases, however, the obtained delay limits fell considerably short of the 2- to 3-min limits obtained in auditory delayed-matching studies using the same test sounds and the same subject. The task differences indicate that working memory functions cannot depend upon memory of the predelay stimulus alone, but must be determined in part by additional processes.

Generalized Relational Matching by Guinea Baboons (Papio papio) in Two-by-Two-Item Analogy Problems

Analogical reasoning is considered the hallmark of human reasoning, but some studies have demonstrated that language- and symbol-trained chimpanzees can also reason analogically. Despite the potential adaptive value of this ability, evidence from other studies strongly suggests that other nonhuman primates do not have this capacity for analogical reasoning. In our three experiments, 6 of 29 baboons acquired the ability to perform a relational matching-to-sample (RMTS) task in which pairs of shapes composed relational displays. Five of these 6 monkeys then transferred this ability to RMTS tasks using novel exemplars of identity (elements in a pair are the same) and nonidentity (elements in a pair are different) relations. This transfer occurred even on trials in which the incorrect pair shared an element with the sample pair with which it was being compared. The baboons retained this ability 12 months later. The findings from our study of symbol-naive monkeys indicate that although language and symbol training facilitate conceptual thinking in nonhuman primates, such training is not a prerequisite for analogical reasoning.

What Meaning Means for Same and Different: Analogical Reasoning in Humans (Homo sapiens), Chimpanzees (Pan troglodytes), and Rhesus Monkeys (Macaca mulatta)

Thus far, language- and token-trained apes (e.g., D. Premack, 1976; R. K. R. Thompson, D. L. Oden, & S. T. Boysen, 1997) have provided the best evidence that nonhuman animals can solve, complete, and construct analogies, thus implicating symbolic representation as the mechanism enabling the phenomenon. In this study, the authors examined the role of stimulus meaning in the analogical reasoning abilities of three different primate species. Humans (Homo sapiens), chimpanzees (Pan troglodytes), and rhesus monkeys (Macaca mulatta) completed the same relational matching-to-sample (RMTS) tasks with both meaningful and nonmeaningful stimuli. This discrimination of relations-between-relations serves as the basis for analogical reasoning. Meaningfulness facilitated the acquisition of analogical matching for human participants, whereas individual differences among the chimpanzees suggest that meaning can either enable or hinder their ability to complete analogies. Rhesus monkeys did not succeed in the RMTS task regardless of stimulus meaning, suggesting that their ability to reason analogically, if present at all, may be dependent on a dimension other than the representational value of stimuli.