Conditional discrimination of series containing either two or three rewarded trials

Series of trials differing only in the number of rewarded trials (2R or 3R series) were used to test rats' ability to learn conditional numerical discriminations. Although the series were conditionally related to initially non-numerical situations, the rats successfully learned the discrimination. It is concluded that these discriminations can plausibly be conceptualized as conditional counting. A pair of transfer tests given after the discriminations were well established suggested that, under these conditions, numerical information will overshadow other non-numerical sources of discrimination made relevant by the transfer shifts.     

Runway acquisition and extinction as a joint function of magnitude of reward and percentage of rewarded acquisition trials

To determine the joint effects of partial reward and reward magnitude on acquisition and extinction rates, and on acquisition and extinction asymptotes, 215 Wistar albino rats were trained in a Hunter straight runway. The experimental design was a 4 × 4 × 2 factorial combining four reward magnitudes, four reward percentages, and two experimenters. The data revealed that the acquisition rate was an increasing function of both percentage and magnitude of reward and that neither reward magnitude nor percentage of reward significantly affected acquisition asymptote. For extinction, it was found that, for continuous schedules, the larger the reward magnitude the less the resistance to extinction and, for partial schedules, the larger the reward magnitude the greater the resistance to extinction. These results were interpreted within the framework of the sequential effects hypothesis (Capaldi, 1966).     

Increased eating in rats deprived of running

Daily food intake in rats was temporarily reduced by the introduction of an activity wheel and temporarily increased by the subsequent removal of the wheel. When this outcome is coupled with the positive relation between food deprivation and running—and food deprivation is seen as a loss of eating rather than as a physiological state—there is the suggestion that the total behavior output of the organism may be regulated as such. Specifically, when the rat is deprived of a behavior that recurrently comprises a large part of its total daily activity, an increase may occur in some other behavior.     

Induction,focused sampling and the law of small numbers

Hilary Kornblith (1993) has recently offered a reliabilist defense of the use of the Law of Small Numbers in inductive inference. In this paper I argue that Kornblith's defense of this inferential rule fails for a number of reasons. First, I argue that the sort of inferences that Kornblith seeks to justify are not really inductive inferences based on small samples. Instead, they are knowledge-based deductive inferences. Second, I address Kornblith's attempt to find support in the work of Dorrit Billman and I try to show that close attention to the workings of her computational model reveals that it does not support Kornblith's argument. While the knowledge required to ground the inferences in question is perhaps inductively derived, Billman's work does not support the notion that small samples provide a reliable basis for our generalizing inferences.     

An inexpensive universal feeder suitable for small numbers of large rations

This report describes a simple universal feeder designed for operant conditioning applications in zoo settings. The apparatus delivers up to six large rations of food. It is portable, easily serviced, and can be constructed in a modest carpentry shop.     

Defensive burying of aversive fluids in rats: The possible role of odor

Defensive burying of flavored fluids paired with lithium chloride injections was examined. Rats showed little inclination to bury conditioned saccharin or salt solutions (Experiments 1 and 2). However, they buried tabasco sauce or dilute milk solutions readily (Experiment 3). It was hypothesized that the amount of olfactory stimulation provided by a solution may determine whether a rat engages in burying. This hypothesis received support in a final experiment which demonstrated that rats readily buried an arbitrarily selected odorous solution which was previously paired with lithium chloride. Thus the present experiments begin the process of identifying the circumstances under which burying does and does not occur.     

Potentiation of odor by taste in rats: tests of some nonassociative factors

The contribution of nonassociative neophobia and sensitization to the potentiation of odor by taste in rats was tested in three experiments. In Experiment 1, neophobia for almond odor (O), saccharin taste (T), and odor-taste compound (OT) cues was tested before and after noncontingent lithium chloride poisoning and compared with conditioned aversions produced by OT-LiCl temporal pairing. The OT compound potentiated unconditioned neophobia, but there was no evidence of poison-enhanced neophobia, disinhibition of neophobia, or sensitization by noncontingent LiCl; temporal pairing produced aversions for the compound and its elements. In Experiment 2, generalization to a novel odor was tested after O-LiCl or compound OT-LiCl pairing. The potentiated odor aversion did not generalize to the novel odor; it was specific to the odor paired with taste and LiCl. In Experiment 3, potentiation of the odor component by a discriminant or nondiscriminant taste component was tested. Potentiation was evident only when a novel discriminant taste was in compound with odor prior to LiCl poisoning. These studies support an associative "indexing" hypothesis of the potentiation effect in rats.     

The role of pattern recognition in children's exact enumeration of small numbers

Enumeration can be accomplished by subitizing, counting, estimation, and combinations of these processes. We investigated whether the dissociation between subitizing and counting can be observed in 4‐ to 6‐year‐olds and studied whether the maximum number of elements that can be subitized changes with age. To detect a dissociation between subitizing and counting, it is tested whether task manipulations have different effects in the subitizing than in the counting range. Task manipulations concerned duration of presentation of elements (limited, unlimited) and configuration of elements (random, line, dice). In Study 1, forty‐nine 4‐ and 5‐year‐olds were tested with a computerized enumeration task. Study 2 concerned data from 4‐, 5‐, and 6‐year‐olds, collected with Math Garden, a computer‐adaptive application to practice math. Both task manipulations affected performance in the counting, but not the subitizing range, supporting the conclusion that children use two distinct enumeration processes in the two ranges. In all age groups, the maximum number of elements that could be subitized was three. The strong effect of configuration of elements suggests that subitizing might be based on a general ability of pattern recognition.     

Free-ranging rhesus monkeys spontaneously individuate and enumerate small numbers of non-solid portions

Fundamental questions in cognitive science concern the origins and nature of the units that compose visual experience. Here, we investigate the capacity to individuate and store information about non-solid portions, asking in particular whether free-ranging rhesus monkeys (Macaca mulatta) quantify portions of a non-solid substance presented in discrete pouring actions. When presented with portions of carrot pieces poured from a cup into opaque boxes, rhesus picked the box with the greatest number of portions for comparisons of 1 vs. 2, 2 vs. 3, and 3 vs. 4, but not for comparisons of 4 vs. 5 and 3 vs. 6. Additional experiments indicate that rhesus based their decisions on both the number of portions and the total amount of food. These results show that the capacity to individuate non-solid portions is not unique to humans, and does not depend on structures of natural language. Further, the fact that rhesus' ability to represent non-solid portions is constrained by the same 4-item limit typically ascribed to the system of parallel individuation that operates over solid objects suggests that the visual system recruits common working memory processes for retaining information about solid objects and non-solid portions. We discuss our results with respect to theories of visual processing, as well as to the role that the human language faculty may have played in both the evolution and development of quantification.