The effect of swimming experience on acquisition and retention of swimming-based taste aversion learning in rats

Swimming endows rats with an aversion to a taste solution consumed before swimming. The present study explored whether the experience of swimming before or after the taste-swimming trials interferes with swimming-based taste aversion learning. Experiment 1 demonstrated that a single preexposure to 20 min of swimming was as effective as four or eight preexposures in causing the interference effect. Experiment 2 found that a single 5-min preexposure was enough to cause the interference effect. Experiment 3 showed that preexposure to swimming interfered with but did not completely thwart the acquisition of swimming-based taste aversion learning. Experiment 4 failed to demonstrate a reliable retroactive interference effect by swimming postexposures. With a modified procedure, however, Experiment 5 successfully demonstrated a reliable effect by four postexposures. The associative and habituation accounts of these results are discussed.     

Visibility pattern of Bose–Fermi mixtures in one-dimensional incommensurate lattices

Abstract

We performed numerical simulations to demonstrate localization phenomena of Bose–Fermi mixture systems on incommensurate optical lattices by changing Bose–Bose and Bose–Fermi interactions. Visibility patterns of the bosons were measured to observe bosonic coherence in various selections of the interaction parameters. We found that the coherence was enhanced with repulsive Bose–Fermi interactions. It was also enhanced with attractive Bose–Fermi interactions but only in certain conditions. The enhancement by repulsive interactions and that by attractive interactions occurred with different mechanisms.     

Group differences in the mutual gaze of chimpanzees (Pan troglodytes)

A comparative developmental framework was used to determine whether mutual gaze is unique to humans and, if not, whether common mechanisms support the development of mutual gaze in chimpanzees and humans. Mother-infant chimpanzees engaged in approximately 17 instances of mutual gaze per hour. Mutual gaze occurred in positive, nonagonistic contexts. Mother-infant chimpanzees at a Japanese center exhibited significantly more mutual gaze than those at a center in the United States. Cradling and motor stimulation varied across groups. Time spent cradling infants was inversely related to mutual gaze. It is suggested that in primates, mutual engagement is supported via an interchangeability of tactile and visual modalities. The importance of mutual gaze is best understood within a perspective that embraces both cross-species and cross-cultural data.     

Orthography and phonology in reading Japanese kanji words: Evidence from the semantic decision task with homophones

Correspondences between spelling and sound for Japanese kanji are complex and deep. The meaning of kanji words has generally been assumed to be accessed directly from orthography without phonological mediation. Experiment 1, however, replicated the findings of Van Orden (1987) that subjects made more false-positive errors on homophone foils than they did on nonhomophone controls in a semantic decision task, although they did so only when the foils were orthographically similar to the correct exemplars, which indicates both orthographic and phonological activations of meaning. Experiment 2 showed the same results when subjects were not required to pronounce the target words after semantic decisions, which indicates automatic phonological activation of kanji words. In Experiment 3, under pattern-masking conditions, this homophony effect was reduced but remained on errors, and the orthographic-similarity effect remained strong on both homophone and nonhomophone foils. These results suggest that both orthography and phonology play an important role in the comprehension of kanji words.     

Plasticity of ability to form cross‐modal representations in infant Japanese macaques

In a previous study, Adachi, Kuwahata, Fujita, Tomonaga & Matsuzawa demonstrated that infant Japanese macaques (Macaca fuscata) form cross‐modal representations of conspecifics but not of humans. However, because the subjects in the experiment were raised in a large social group and had considerably less exposure to humans than to conspecifics, it was an open question whether their lack of cross‐modal representation of humans simply reflected their lower levels of exposure to humans or was caused by some innate restrictions on the ability. To answer the question, we used the same procedure but tested infant Japanese macaques with more extensive experience of humans in daily life. Briefly, we presented monkeys with a photograph of either a monkey or a human face on an LCD monitor after playing a vocalization of one of these two species. The subjects looked at the monitor longer when a voice and a face were mismatched than when they were matched, irrespective of whether the preceding vocalization was a monkey's or a human's. This suggests that once monkeys have extensive experience with humans, they will form a cross‐modal representation of humans as well as of conspecifics.     

Perception of emergent configurations in humans (Homo sapiens) and chimpanzees (Pan troglodytes)

We examined the perceptions of emergent configurations in humans and chimpanzees using a target-localization task. The stimulus display consisted of a target placed among multiple identical distractors. The target and distractors were presented either solely, within congruent contexts in which salient configurations emerge, or within incongruent contexts in which salient configurations do not emerge. We found that congruent contexts had similar facilitative effects on target localization by humans and chimpanzees, whereas similar disruptive effects emerged when the stimuli were presented within incongruent contexts. When display size was manipulated, targets under the congruent-context condition were localized in a parallel manner, but those under the no-context and incongruent-context conditions were localized in a serial manner by both species. These results suggest that both humans and chimpanzees perceive emergent configurations when targets and distractors are presented within certain congruent contexts and that they process such emergent configurations preattentively.     

Slowly walking down to the more food: relative quantity discrimination in African spurred tortoises (Centrochelys sulcata)

Animal Cognition - Quantity discrimination, is thought to be highly adaptive as it allows an organism to select greater amounts of food or larger social groups. In contrast to mammals, the...     

Relative numerosity discrimination by chimpanzees (Pan troglodytes): evidence for approximate numerical representations

Two adult chimpanzees were trained on a relative “numerosity” discrimination task. In each trial, two arrays containing different numbers of red dots were presented on a CRT monitor. The subjects were required to choose the array containing the larger number of dots. In Experiment 1, using numerosities between 1 and 8, 28 different pairs were presented repeatedly, and accuracy scores were analyzed to explore which cues the chimpanzee subjects utilized to perform the task. Multiple regression analyses revealed that the subjects’ performance was (1) not simply controlled by the “numerical” difference between arrays, but that it was (2) best described by Fechner’s Law–that is accuracy increased linearly with the logarithmic value of the numerical difference between arrays divided by the number in the larger of the two arrays. This relationship was maintained when using much larger numerosities (Experiment 3). In Experiment 2, the chimpanzees were tested on the effects of total area and density by manipulating dot size and presentation area. The results revealed that these factors clearly affected the subjects’ performance but that they could not alone explain the results, suggesting that the chimpanzees did use relative numerosity difference as a discriminative cue.     

Renewal of operant performance formerly eliminated by omission or noncontingency training upon return to the acquisition context

Renewal of operant performance formerly eliminated by omission or noncontingency training was explored in two experiments with rats. When pressing a lever was trained with food reinforcement in one context (A) and then eliminated in a second context (B), responding was renewed by returning the rats to the original context (A). This ABA renewal effect was demonstrated in Experiment 1 when the elimination training was an omission procedure (delivery of food for withholding responding) and in Experiment 2 when it was a noncontingency procedure (delivery of food irrespective of responding). Because omission training (differential reinforcement of other behavior) and noncontingency training have been used in applied settings as effective procedures to reduce undesired human behaviors, the clinical implications of our findings for the relapse of undesirable behavior were discussed.