Cantlon, J. F., & Brannon, E. M. (2007). How Much Does Number Matter to a Monkey (Macaca mulatta)? Journal of Experimental Psychology: Animal Behavior Processes, 33(1), 32–41.
Abstract: Although many animal species can represent numerical values, little is known about how salient number is relative to other object properties for nonhuman animals. In one hypothesis, researchers propose that animals represent number only as a last resort, when no other properties differentiate stimuli. An alternative hypothesis is that animals automatically, spontaneously, and routinely represent the numerical attributes of their environments. The authors compared the influence of number versus that of shape, color, and surface area on rhesus monkeys' (Macaca mulatta) decisions by testing them on a matching task with more than one correct answer: a numerical match and a nonnumerical (color, surface area, or shape) match. The authors also tested whether previous laboratory experience with numerical discrimination influenced a monkey's propensity to represent number. Contrary to the last-resort hypothesis, all monkeys based their decisions on numerical value when the numerical ratio was favorable.
|
Gray, E. R., & Spetch, M. L. (2006). Pigeons Encode Absolute Distance but Relational Direction From Landmarks and Walls. Journal of Experimental Psychology: Animal Behavior Processes, 32(4), 474–480.
Abstract: In recent studies, researchers have examined animals' use of absolute or relational distances in finding a hidden goal. When trained with an array of landmarks, most animals use the default strategy of searching at an absolute distance from 1 or more landmarks. In contrast, when trained in enclosures, animals often use the relationship among walls. In the present study, pigeons were trained to find the center of an array of landmarks or a set of short walls that did not block external cues. Expansion tests showed that both groups of pigeons primarily used an absolute distance strategy. However, on rotational tests, pigeons continued to search in the center of the array, suggesting that direction was learned in relation to array.
|
Treichler, F. R., & Van Tilburg, D. (1996). Concurrent Conditional Discrimination Tests of Transitive Inference by Macaque Monkeys: List Linking. J Exp Psychol Anim Behav Process, 22(1), 105–117.
Abstract: Processing of serial information was assessed by training six macaques on a five-item list of objects arranged into the four conditional pairs, A-B+, B-C+, C-D+, and D-E+. An analogous list (F through J) was similarly trained. Subsequently, both lists were linked by training on E-F+, a pair that provided adjacent elements from each list. Then, all unique and trained object pairs from both lists were presented as a test. Results indicated that the objects were retained as a single, linearly organized list with choice accuracy directly related to interitem distance between paired objects. A second experiment explored the consequences of incidence of conflicting information on list organization. In both experiments, selections depended on representational processes and supported the view that monkeys and pigeons retain serial lists in qualitatively different ways.
|
