Same/different abstract-concept learning by pigeons.

Eight pigeons were trained and tested in a simultaneous same/different task. After pecking an upper picture, they pecked a lower picture to indicate same or a white rectangle to indicate different. Increases in the training set size from 8 to 1,024 items produced improved transfer from 51.3% to 84.6%. This is the first evidence that pigeons can perform a two-item same/different task as accurately with novel items as training items and both above 80% correct. Fixed-set control groups ruled out training time or transfer testing as producing the high level of abstract-concept learning. Comparisons with similar experiments with rhesus and capuchin monkeys showed that the ability to learn the same/different abstract concept was similar but that pigeons require more training exemplars. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Concept learning at different levels of abstraction by pigeons, monkeys, and people.

Pigeon, monkey, and human subjects were trained on three two-choice picture discrimination problems that varied in level of abstraction. At the most concrete level, subjects were rewarded for choosing pictures of a single species of bird, the common kingfisher, and nonrewarded for choosing pictures of other birds. At an intermediate level of abstraction, subjects were required to discriminate bird pictures as a general category from pictures of nonbird animals. As the most abstract problem, animal pictures in general were S+ items, and nonanimal pictures were S– items. Tests with novel probe pairs of pictures in Experiment 1 indicated that human subjects rapidly mastered all three concepts. Pigeons and monkeys performed well on the concrete kingfisher problem but not on the more abstract birds and animals problems. Although this initial experiment suggested that concept learning in pigeons and monkeys might be limited to concrete categories, further training with more exemplars in Experiment 3 revealed accurate identification of animal pictures in contrast to nonanimal pictures. On the other hand, both pigeons and monkeys showed an inability to discriminate novel bird pictures from pictures of other classes of animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer in artificial grammar learning: A reevaluation.

This article covers methodological and theoretical issues in artificial grammar learning. Arguments that such tasks are mediated by abstract knowledge (e.g., A. S. Reber, see record 1991-00330-001) are based primarily on evidence from transfer experiments, where the surface vocabulary is changed between learning and test items. Because of a number of methodological concerns, the small magnitudes of artificial grammar learning effects generally are difficult to interpret. Possible solutions are offered here. Furthermore, even reliable transfer effects imply neither that subjects have acquired abstract knowledge of the underlying grammar nor that they are performing a process of abstract analogy from memorized whole exemplars. Models that learn only surface fragments of the training stimuli and perform abstraction at test rather than during learning are wholly consistent with transfer phenomena. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Representation of serial order in pigeons (Columba livia).

In Experiment 1, 2 groups of pigeons were trained to respond to either a 4-item (A→B→C→D) or 5-item (A→B→C→D→E) list. After learning their respective list, half of the subjects were trained on a positive pair with reinforcement provided when pairs were responded to in the order true to that of the original sequence (4-item: B→C; 5-item: B→D). The remaining subjects were trained on a negative pair with reinforcement provided for responding to the pairs in the order opposite to that learned in the original sequence (4-item: C→B; 5-item: D→B). Subjects in the positive pair condition learned their respective pair faster than did subjects in the negative pair condition. In Experiment 2, after reaching criterion on a 4-item list, subjects received 16 BC probe trials spread across 4 sessions of training. Subjects performed significantly above chance on the probe trials. The performance of our subjects in Experiments 1 and 2 demonstrates that, similar to monkeys, pigeons form a representation of the lists that they learn. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monkey memory: Same/different concept learning, serial probe acquisition, and probe delay effects.

Three rhesus monkeys were trained and tested in a same/different task with 6 successive sets of 70 item pairs to an 88% accuracy on each set. Their poor initial transfer performance (55% correct) with novel stimuli improved dramatically to 85% correct following daily item changes in the training stimuli. They acquired a serial-probe-recognition (SPR) task with variable (1–6) item list lengths. This SPR acquisition, although gradual, was more rapid for the monkeys than for pigeons similarly trained in a companion experiment by H. C. Santiago and A. A. Wright (see record 1985-19336-001). Testing with a fixed list length of 4 items at different delays between the last list item and the probe test item revealed changes in the serial-position function: a recency effect (last items remembered well) for 0-sec delay; recency and primacy effects (first and last list items remembered well) for 1-, 2-, and 10-sec delays, and only a primacy effect for a 30-sec delay. Results are discussed in relation to theories of memory processing. (60 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Artificial grammar learning depends on implicit acquisition of both abstract and exemplar-specific information.

The contributions of exemplar-specific and abstract knowledge to artificial grammar learning were examined in amnesic patients and controls. In Experiment 1, grammatical rule adherence and chunk strength exerted separate effects on grammaticality judgments. Amnesic patients exhibited intact classification performance, demonstrating the same pattern of results as controls. In Experiment 2, amnesic patients exhibited impaired declarative memory for chunks. In Experiment 3, both amnesic patients and controls exhibited transfer when tested with a letter set different than the one used for training, although performance was better when the same letter sets were used at training and test. The results suggest that individuals learn both abstract information about training items and exemplar-specific information about chunk strength and that both types of learning occur independently of declarative memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanisms of inferential order judgments in humans (Homo sapiens) and rhesus monkeys (Macaca mulatta).

If A > B, and B > C, it follows logically that A > C. The process of reaching that conclusion is called transitive inference (TI). Several mechanisms have been offered to explain transitive performance. Scanning models claim that the list is scanned from the ends of the list inward until a match is found. Positional discrimination models claim that positional uncertainty accounts for accuracy and reaction time patterns. In Experiment 1, we trained rhesus monkeys (Macaca mulatta) and humans (Homo sapiens) on adjacent pairs (e.g., AB, BC, CD, DE, EF) and tested them with previously untrained nonadjacent pairs (e.g., BD). In Experiment 2, we trained a second list and tested with nonadjacent pairs selected between lists (e.g., B from List 1, D from List 2). We then introduced associative competition between adjacent items in Experiment 3 by training 2 items per position (e.g., B?C?, B?C?) before testing with untrained nonadjacent items. In all 3 experiments, humans and monkeys showed distance effects in which accuracy increased, and reaction time decreased, as the distance between items in each pair increased (e.g., BD vs. BE). In Experiment 4, we trained adjacent pairs with separate 9- and 5-item lists. We then tested with nonadjacent pairs selected between lists to determine whether list items were chosen according to their absolute position (e.g., D, 5-item list > E, 9-item list), or their relative position (e.g., D, 5-item list     

Extent and limits of the matching concept in monkeys (Cebus apella).

Two experiments with 11 monkeys investigated the extent and limits of the matching concept. In Exp I, 8 Ss that were experimentally naive with regard to visual stimuli were trained on identity matching with a 2-sample set based on 2-dimensional stimuli. On a subsequent test employing 2 new samples, 4 of the 8 Ss applied the matching rule to the new sample stimuli (as defined by a transfer criterion). Three of these Ss showed substantial savings in learning to match the new samples; 2 of the 3 Ss transferred the matching rule when given a 2nd test with 2 new samples, and the 3rd S showed immediate and complete transfer when tested with a 3rd pair of new stimuli. Results indicate a stronger representation of the matching concept in monkeys than has been demonstrated with pigeons, even in comparable assessment conditions. However, in Exp II, 4 Ss from Exp I failed to transfer the matching rule to steady vs flashing green samples, indicating that the matching concept did not immediately extend beyond the general class of visual stimuli with which it was developed. These and related research findings suggest that representation of the matching concept in animals varies along a specificity–abstractness dimension, reflecting the degree to which the concept is tied to the conditions and context of its development. (45 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The comparative psychology of same-different judgments by humans (Homo sapiens) and monkeys (Macaca mulatta).

The authors compared the performance of humans and monkeys in a Same-Different task. They evaluated the hypothesis that for humans the Same-Different concept is qualitative, categorical, and rule-based, so that humans distinguish 0-disparity pairs (i.e., same) from pairs with any discernible disparity (i.e., different); whereas for monkeys the Same-Different concept is quantitative, continuous, and similarity-based, so that monkeys distinguish small-disparity pairs (i.e., similar) from pairs with a large disparity (i.e., dissimilar). The results supported the hypothesis. Monkeys, more than humans, showed a gradual transition from same to different categories and an inclusive criterion for responding Same. The results have implications for comparing Same-Different performances across species--different species may not always construe or perform even identical tasks in the same way. In particular, humans may especially apply qualitative, rule-based frameworks to cognitive tasks like Same-Different. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhesus monkeys (Macaca mulatta) rapidly learn to select dominant individuals in videos of artificial social interactions between unfamiliar conspecifics.

Social animals, such as primates, must behave appropriately in complex social situations such as dominance interactions. Learning dominance information through trial and error would be dangerous; therefore, cognitive mechanisms for rapid learning of dominance information by observation would be adaptive. We used a set of digitally edited artificial social interactions to examine whether rhesus monkeys (Macaca mulatta) can learn dominance relationships between unfamiliar conspecifics through observation. Our method allowed random assignment of stimulus monkeys to ranks in an artificial hierarchy, controlling for nonbehavioral cues that could indicate dominance. Subject monkeys watched videos depicting 1 stimulus monkey behaving dominantly toward another and were rewarded for selecting the dominant individual. Monkeys rapidly learned this discrimination across 5 behavior types in Experiment 1 and transferred performance to novel videos of new individuals in Experiment 2. In addition, subjects selected the dominant individual more often than expected by chance in probe videos containing no behavioral dominance information, indicating some retention of the relative dominance status of stimulus monkeys from training. Together, our results suggest that monkeys can learn dominance hierarchies through observation of third-party social interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Representation of serial order in monkeys (Cebus apella).

Cebus monkeys were trained on a five-item serial learning task, symbolized as ABCDE; the initial stages of training were on the shorter subseries AB, ABC, and ABCD. To assess the monkeys' knowledge of the sequential position of each item, pair-wise tests were given to 2 subjects after acquisition of the ABCD series and to 4 subjects after reaching criterion on the ABCDE series. In both tests, the monkeys performed at high levels on the interior pairs, which was BC for the ABCD series, and BC, BD, and CD for the ABCDE series. These results, as well as the orderly relations observed in the pair-wise tests between first-item response latency and first-term position and between second-item response latency and number of missing items, indicated that the monkeys had developed a well-organized internal representation of the four- and five-item series. Although pigeons are also capable of learning four-item and five-item series, they apparently do not develop a comparable representational structure. The disparity between the monkeys' and pigeons' representational competence for serial order is predictable from the difference in their capabilities for associative transivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Matching-to-sample abstract-concept learning by pigeons.

Abstract concepts--rules that transcend training stimuli--have been argued to be unique to some species. Pigeons, a focus of much concept-learning research, were tested for learning a matching-to-sample abstract concept. Five pigeons were trained with three cartoon stimuli. Pigeons pecked a sample 10 times and then chose which of two simultaneously presented comparison stimuli matched the sample. After acquisition, abstract-concept learning was tested by presenting novel cartoons on 12 out of 96 trials for 4 consecutive sessions. A cycle of doubling the training set followed by retraining and novel-testing was repeated eight times, increasing the set size from 3 to 768 items. Transfer performance improved from chance (i.e., no abstract-concept learning) to a level equivalent to baseline performance (>80%) and was similar to an equivalent function for same/different abstract-concept learning. Analyses assessed the possibility that item-specific choice strategies accounted for acquisition and transfer performance. These analyses converged to rule out item-specific strategies at all but the smallest set-sizes (3-24 items). Ruling out these possibilities adds to the evidence that pigeons learned the relational abstract concept of matching-to-sample. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies of concept formation by stumptailed monkeys: Concepts humans, monkeys, and letter A..

Natural concepts were studied in 3 of 4 experiments with 4 stumptailed monkeys, using a series of photographic slides. The concept of humans was studied in Exp I, using scenes with or without one or more humans present, and the concept of monkeys was studied in Exp II, using scenes with one or more monkeys and scenes with other types of animals. In both experiments, Ss were trained on 1 set of slides using a conditional spatial discrimination task and tested for transfer to a new set. All Ss tested showed positive transfer, performing at a higher level with new slides initially than they had during original learning, though well below the level reached by the end of original learning. The initial transfer could not be explained by learning of individual slides, though such learning was clearly a strong factor in the overall performance. Performance was better when humans were a prominent part of the scene. In Exp III, the discrimination task was changed to go/no-go. There was some improvement in discrimination but not in transfer. In Exp IV, Ss were trained to discriminate the letter A from the numeral 2 in a variety of typefaces, and they transferred the discrimination at a high level to a set of these stimuli in new typefaces. Results are consistent with a concept interpretation. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ordinal Representation of Numeric Quantities by Brown Capuchin Monkeys (Cebus apella).

Using techniques established by E. M. Brannon and H. S. Terrace (2000) with rhesus macaques (Macaca mulatta), the authors tested the ability of brown capuchins (Cebus apella) to order arrays of items ranging in quantity from 1 to 9. Three monkeys were trained on a touch screen to select the quantities 1-4 in ascending order. The monkeys exhibited successful transfer of this ability to novel representations of the quantities 1-4 and to pairs of the novel quantities 5-9. Patterns of responding with respect to numeric distance and magnitude were similar to those seen in human subjects, suggesting the use of similar psychological processes. The capuchins demonstrated an ordinal representation of quantity equivalent to that shown in Old World monkeys. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhesus Macaques (Macaca mulatta) Categorize Unknown Conspecifics According to Their Dominance Relations.

The authors trained 3 adult male rhesus macaques (Macaca mulatta) to categorize pairs of unknown conspecifics presented in a video according to the dominance status of the videotaped monkeys. The subjects were trained to choose the dominant monkey for a category of films (e.g., films showing 1 monkey chasing another); then, new films were presented involving different conspecifics, and the monkeys' first responses to this new category of behavior (e.g., monkeys fighting) were taken as evidence of transfer. Two subjects were able to generalize categorical judgments of dominance to new films involving new behaviors. These findings seem to indicate that monkeys can use abstract social concepts and are aware of the social relationships within their group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response strategies inlist learning by orangutans (Pongo pygmaeus × P. abelii).

Rhesus monkeys (Macaca mulatta) develop strategies to acquire and execute serial lists (K. B. Swartz & S. A. Himmanen, 2001). Serial probe recognition studies of list memory have demonstrated similarities across monkeys and humans (S. F. Sands & A. A. Wright, 1980). The present study extended the investigation of list learning and memory to determine whether orangutans (Pongo pygmaeus × P. abelii) would show evidence of subjective organization of photographic lists in a manner similar to that shown by humans learning a list of unrelated words (E. Tulving, 1962). No evidence for the effective use of a subjective organization strategy was found, but the orangutans developed a right-to-left spatial response strategy, which emerged during the acquisition of 5-item lists. This strategy was an effective way to reduce the load on working memory when presented with a complex array of items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for pictures of upright and inverted primate faces in humans (Homo sapiens), squirrel monkeys (Saimiri sciureus), and pigeons (Columba livia).

Humans (Homo sapiens) and squirrel monkeys (Saimiri sciureus) were tested for memory of upright and inverted primate faces. Working memory was tested in Exp 1 with a delayed matching-to-sample procedure, and reference memory was examined in Exp 2 by requiring Ss to learn to discriminate between successive pairs of upright or inverted pictures. Both human and monkey subjects showed better working memory for upright than for inverted human faces and better reference memory for upright than for inverted human and great ape faces. In Exp 3, reference memory tests with pigeons (Columba livia) showed no effects of inversion on rate of learning with face pictures. We argue that these findings cannot be explained easily by an individual primate's lifetime experiences with primate faces. We suggest that similar evolved mechanisms for primate face recognition in people and monkeys are responsible for the pattern of data reported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual discrimination and reversal learning in the aged monkey (Macaca mulatta).

Visual discrimination and reversal learning were assessed in young adult (10–12 yrs old, n?=?4) and aged (23–27 yrs old, n?=?5) female rhesus monkeys. Performance was comparable across age groups in many tasks, suggesting that the acquisition of stimulus–reward associations remains largely intact in the aged monkey. Most older Ss, however, required more training than any young animal to learn an initial pattern discrimination. In combination with previous findings (P. R. Rapp and D. G. Amaral; 1989) from the same groups of monkeys, these data suggest that deficits in attending to the relevant stimulus features in novel testing procedures may contribute to poor performance in aged Ss across a variety of learning and memory tasks. In addition, preliminary findings from a discrimination probe procedure raise the possibility that aged Ss may adopt alternate testing strategies that compensate for some aspects of age-dependent cognitive dysfunction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Picture mediation in abstract-concrete paired associates

The present study investigated the hypothesis that pictures of abstract-concrete paired associates would serve to make the abstract stimulus member more concrete thereby enhancing the learning process. 60 subjects were equally divided into 6 groups, varying conditions of concreteness and abstractness of the stimulus items and pictures or no picture. The results supported the basic proposition that the picture mediation presented during the learning-testing condition facilitated the learning of the abstract paired associates.     

Role of intelligence and task difficulty in the affective learning styles of children with high and low self-concepts.

Fifth-graders prerated both abstract and concrete nouns for likability, and paired-associate lists were constructed by pairing nouns (liked with liked and disliked with disliked). As predicted, the high self-concept (Piers-Harris Self-Concept Scale) children learned their liked noun pairs more efficiently than their disliked pairs, while the low self-concept children reversed and learned their disliked noun pairs more readily. Further analysis revealed that these self-concept patterns were most pronounced for low-IQ (Lorge-Thorndike Intelligence Test) children. High-IQ children, who were superior to low-IQ children in overall learning, showed no preference for their affective evaluations in learning. Increasing task difficulty (e.g., by increasing work abstractness) resulted in a tendency to learn disliked items more readily than liked items. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)