牛谷 智一

<p>We review use of multiple landmarks in navigational behavior by humans and nonhuman animals focusing on three important aspects of spatial learning and cognition: Cognitive map, spatial integration, and configuration of multiple landmarks. Animals use multiple strategies for spatial navigation rather than a single strategy and flexibly choose an appropriate strategy in accordance with each environmental condition. Concerning the goal searching in humans, for example, whether it is based on information from multiple landmarks or from just one landmark would depend on the salience of the landmarks. Our conclusion is that it is more important what strategies or spatial information animals choose under what conditions than whether or not they have and use the strategies.</p>

Landmark-based goal-searching tasks that were similar to those for pigeons (Ushitani &amp Jitsumori, 2011) were provided to human participants to investigate whether they could learn and use multiple sources of spatial information that redundantly indicate the position of a hidden target in both an open field (Experiment 1) and on a computer screen (Experiments 2 and 3). During the training in each experiment, participants learned to locate a target in 1 of 25 objects arranged in a 5 × 5 grid, using two differently colored, arrow-shaped (Experiments 1 and 2) or asymmetrically shaped (Experiment 3) landmarks placed adjacent to the goal and pointing to the goal location. The absolute location and directions of the landmarks varied across trials, but the constant configuration of the goal and the landmarks enabled participants to find the goal using both global configural information and local vector information (pointing to the goal by each individual landmark). On subsequent test trials, the direction was changed for one of the landmarks to conflict with the global configural information. Results of Experiment 1 indicated that participants used vector information from a single landmark but not configural information. Further examinations revealed that the use of global (metric) information was enhanced remarkably by goal searching with nonarrow-shaped landmarks on the computer monitor (Experiment 3) but much less so with arrow-shaped landmarks (Experiment 2). The General Discussion focuses on a comparison between humans in the current study and pigeons in the previous study.

Three experiments that were carried out in series with 5 pigeons used novel training methods to investigate the rapid visual processing of picture stimuli by pigeons. On each trial, a sequence containing 1 of 2 bird pictures (the target) and nontarget bird pictures (the distractors) was presented. After the termination of the last item in the sequence, the pigeons were required to choose 1 of 2 colored squares corresponding to the target presented in the preceding sequence. The pigeons learned the task with 2-item lists (1 target and 1 distractor) in Experiment1 and with 3-item lists (1 target and 2 distractors) in Experiment 2. The pigeons showed better performance when the target appeared last in the sequence (a recency effect) and poorer performance the shorter the item duration. In Experiment 3, the pigeons were tested with 3-item lists, but on half the trials 2 distractors were replaced with blanks for example, a target-distractor-distractor trial became a target-blank-blank trial and performances on these trials were compared. When the item duration was 80 ms or greater, omission of the distractors did not have an effect of increasing performance, suggesting that the recency effect was determined by simple passage of time. With the item durations less than 80 ms, the distractors interfered with memory of the target. When the distractors were omitted, performance remained slightly above chance even at the shortest, 17-ms, item duration. These findings indicate that pigeons are equipped with visual mechanisms that enable them to process visual stimuli rapidly.

Normally, worker honey bees (Apis mellifera) begin foraging when more than 2 weeks old as adults, but if individual bees or the colony is stressed, bees often begin foraging precociously. Here, we examined whether bees that accelerated their behavioural development to begin foraging precociously differed from normal-aged foragers in cognitive performance. We used a social manipulation to generate precocious foragers from small experimental colonies and tested their performance in a free-flight visual reversal learning task, and a test of spatial memory. To assess spatial memory, bees were trained to learn the location of a small sucrose feeder within an array of three landmarks. In tests, the feeder and one landmark were removed and the search behaviour of the bees was recorded. Performance of precocious and normal-aged foragers did not differ in a visual reversal learning task, but the two groups showed a clear difference in spatial memory. Flight behaviour suggested normal-aged foragers were better able to infer the position of the removed landmark and feeder relative to the remaining landmarks than precocious foragers. Previous studies have documented the cognitive decline of old foragers, but this is the first suggestion of a cognitive deficit in young foragers. These data imply that worker honey bees continue their cognitive development during the adult stage. These findings may also help to explain why precocious foragers perform quite poorly as foragers and have a higher than normal loss rate.

Landmark cues are especially important in spatial cognition, because the processing of landmarks is seen at an early stage of cognitive map formation. Previous studies have indicated that animals are capable of conducting goal searches using multiple landmarks. We reviewed studies on the competition and integration of spatial information regarding multiple landmarks. It was considered that knowledge about the processing of landmarks would lead to an understanding about the competition that occurs among multiple landmarks and about the spatial cognition leading to the development of multiple landmarks in cognitive maps. These issues have been independently investigated in the contexts of cognitive mapping and associative learning. It is concluded that cue competitions among multiple landmarks are acquisition processes and it is proposed that competition for cues precedes the integration process in cognitive map formation.

Pigeons were trained to classify composite faces of two categories created by mimicking the structure of basic-level categories, with each face consisting of an item-specific component and a common component diagnostic for its category. Classification accuracy increased as the proportion of common components increased, regardless of familiar and novel item-specific components, with the best discrimination occurring at untrained original faces used as the common components. A no-categorization control condition suggested that categorization gives rise to equivalence for item-specific components and distinctiveness for degrees of prototypicality. When some item-specific components were shared by exemplars of the contrasting categories, those that were not overlapping between the categories became the effective cues for the pigeons' responses. Implications of these results are discussed in the context of current categorization and associative learning theories.

Three touch screen-based experiments were conducted to investigate whether pigeons would learn to use configural information about a goal's location in relation to a multiple-landmark array. In Experiment 1, 4 pigeons (Columba livia) were trained to peck a computer monitor at a location that constituted the third vertex of a hypothetical triangle defined by 2 different landmarks. The landmarks appeared in 3 orientations during the training, and the pigeons' goal-searching ability easily transferred to the landmarks presented in 3 novel orientations. Each landmark was asymmetric, so we next examined whether the pigeons used (a) the small-scale, local orientation information that could be inferred from each landmark individually, or (b) the large-scale, configural information that could be inferred from the spatial arrangement of multiple landmarks taken as a whole. Even when each single landmark appeared by itself, the pigeons were, able to locate the goal accurately, suggesting that the large-scale, configural information was not essential. However, when 1 landmark locally pointed to a location that was consistent with the triangular configuration and the other landmark locally pointed to a different location, the pigeons predominantly pecked at the configurally array-consistent location. These results suggest that the pigeons redundantly learned both the large-scale, configural strategy and the local, single-landmark strategy, but they mainly used the latter information, and used the former information solely to disambiguate conflicts when the 2 landmarks pointed toward different targets. Such flexible learning and use of redundant information may reflect the pigeons' adaptation to unstable wild environments during their evolutionary history.

Two experiments investigated the processing of global and local information by pigeons. In Experiment 1, pigeons were trained to discriminate four hierarchical stimuli composed of two letters at global level and two other letters at local level. Color frames predicted the level to be tested in the subsequent two-alternative forced-choice test. The pigeons learned to discriminate the global/local compound stimuli and then showed successful transfer to the stimuli composed of novel letters that were irrelevant to the subsequent test. In Experiment 2, new pigeons were trained with the stimuli ...

Arithmetic-like reasoning has been demonstrated in various animals in captive and seminatural environments, but it is unclear whether such competence is practiced in the wild. Using a hypothetical foraging paradigm, we demonstrate that wild vervet monkeys spontaneously adjust their foraging behavior deploying arithmetic-like reasoning. Presented with arithmetic-like problems in artificially controlled feeding conditions, all the monkeys tested attempted to retrieve artificial prey according to the quantity of the remainder when the task involved one subtraction only (i.e., 2-1), while one monkey out of four did so when it was sequentially subtracted twice (i.e., 2-1-1). This monkey also adjusted his foraging behavior according to the quantity of the reminder for a task requiring stepwise mental manipulation (i.e., (2-1)-1), though the results became less evident. This suggests that vervet monkeys are capable of spontaneously deploying mental manipulations of numerosity for cost-benefit calculation of foraging but that the extent of such capacity varies among individuals. Different foraging strategies might be deployed according to different levels of mental manipulation capacity in each individual in a given population. In addition to providing empirical data, the current study provides an easily adaptable field technique that would allow comparison across taxa and habitat using a uniform method. © 2011 Sayaka Tsutsumi et al.

A comparative study was conducted to investigate whether the search for a target letter was facilitated when the target and prime (preceding stimulus) letters were identical. Pigeons (Section 2) and human participants (Section 3) were first trained to search for "A" among "Y"s and "E" among "D"s in a condition in which a square shape appeared as the prime (Neutral condition). In subsequent testing, a prime was identical either to the corresponding target (Target-priming condition) or to the distractor (Distractor-priming condition). Humans and pigeons responded differently to the two priming conditions. On early trials, the Target prime facilitated search in humans, reducing reaction times (RTs) to targets. In pigeons, however, RTs were longer with Target primes, suggesting that pre-exposure to target letters may directly inhibit the search for targets in subsequent search displays. Furthermore, pre-exposure to the distractor letters may inhibit the processing of the distractor. On later trials, RTs of humans were faster in both priming conditions than in the Neutral condition, suggesting that expectation of a target facilitated search ("Y" predicted "A" and "D" predicted "E"). In contrast, the pigeons showed no evidence of expectation-based facilitation, with constant slowing effects of the Target prime extending across sessions. Possible mechanisms underlying such a slowing priming effect in pigeons were discussed. (C) 2010 Elsevier B.V. All rights reserved.

We conducted three experiments to investigate how object-based components contribute to the attentional processes of chimpanzees and to examine how such processes operate with regard to perceptually structured objects In Experiment 1. chimpanzees responded to a spatial Cueing task that required them to touch a target appearing at either end of two parallel rectangles We compared the time involved in shifting attention (cost of attentional shift) when the locations of targets were cued and non cued. Results showed that the cost of the attentional shift within one rectangle was smaller than that beyond the object's boundary, demonstrating object-based attention in chimpanzees. The results of Experiment 2, conducted with different Stimulus configurations, replicated the results of Experiment 1. supporting that object-based attention operates in chimpanzees. In Experiment 3, the cost of attentional shift within a Cued but partly occluded rectangle was shorter than that within a rectangle that was cued but divided in the middle. The results suggest that the attention of chimpanzees is activated not only by an explicit object but also by fragmented patches represented as an object at a higher-order perceptual level. Chimpanzees' object-based attention may be similar to that of humans. (C) 2010 Elsevier Ltd. All rights reserved.

In our target article published in the latest special issue of the Japanese Journal of Animal Psychology, we proposed a new framework of species comparison for studies of animal psychology in which the generalist and evolutionist approaches were incorporated. The 13 open peer commentaries to the target article, the pros and cons, provided valuable criticisms on our proposal. Although generalists were skeptical of scientific validity of the evolutionist approach due to its difficulty of experimental examination, we think that species comparison allows us to test evolutionist hypotheses with regard to adaptive values (ultimate causes) of certain psychological processes in a falsifiable manner. In the present paper, we reemphasized that species comparison has a critical role in studies of animal psychology and that the examination of ultimate cause is as important as that of proximate causes of psychological processes.

The purpose of this article was to address issues on what the role of species comparison is for the studies of animal psychology. Whereas some people think that the comparison has a critical role in their approaches, others do not. We classify these two groups of people as evolutionists and generalists, respectively. In the evolutionary approach, different species are compared to examine correlations between specific selective pressures (such as caching food) and cognitive abilities (such as spatial learning) in animals. In contrast, different species of animals are compared to examine universal principles of learning in the generalist approach. Although the generalists' ideas of the "universal" principles of learning provide parsimonious explanations of animals' behavior, they tend to underestimate influences of selective pressures on learning and cognition. We therefore propose a new framework for the study of animal learning and cognition; it is based on the evolutionary approach and examines ultimate causes of diversities of learning and cognition but includes ideas of generalists' approaches to explain proximate causes.

Six tree shrews and 8 rats were tested for their ability to infer transitively in a spatial discrimination task. The apparatus was a semicircular radial-arm maze with 8 arms labeled A through H. In Experiment 1, the animals were first trained in sequence on 4 discriminations to enter 1 of the paired adjacent arms, AB, BC, CD, and DE, with right (or left, for half the animals) symbols signifying positive options then they were tested with the previously unused pair of arms, FH. All tree shrews and 4 rats transitively chose H (or F for half the animals). In Experiment 2, all tree shrews and 5 rats transitively chose H (or F) on 3-option tests of FGH. The results suggest that these animals used transitive relation in solving novel problems.

The authors examined how pigeons (Columba livia) perform on 2-dimensional maze tasks on the LCD monitor and whether the pigeons preplan the solution before starting to solve the maze. After training 4 pigeons to move a red square (the target) to a blue square (the goal) by pecking, the authors exposed them to a variety of detour tasks having lines as a barrier. A preview phase was introduced, during which the pigeons were not allowed to peck at the monitor. Results of a set of experiments suggest that our pigeons successfully learned to solve these tasks, that they came to take an efficient strategy as the barriers became complex, and that they possibly preplan its solution, at least on familiar, well-practiced tasks.

Whereas many non-human species have been demonstrated to visually complete partly occluded figures, pigeons have been repeatedly failed to do so. We asked whether this failure reflected the pigeons' lack of perceptual process for completion or their decision among completed and non-completed figures. Four pigeons searched for a red lozenge target having one of its four contours punched in a rectangular edge out among three intact lozenges. All of these four stimuli had a white square next to them. After obtaining consistent search performances, the pigeons were tested with the punched target in a variety of locations relative to the white square, including right at the edges. Humans tested in the same task needed longer times before detecting the target when the square was placed right at the punched edge, suggesting automatic completion in humans. In contrast, the pigeons showed no similar difficulty. This result has two important suggestions: first, pigeons fail to complete partially occluded objects at the perceptual level, and second, this lack of completion is sometimes advantageous for them. (c) 2005 Elsevier B.V. All rights reserved.

We investigated whether pigeons perceived relative motion of more than one object. We trained pigeons to match a white target dot moving vertically at a constant speed to one color and the same dot moving diagonally to another. In Experiment 1, we presented an additional yellow dot (accompanying dot) moving horizontally near the target. We hypothesized that the pigeons would match the diagonal motion to the color for "vertical motion" and vice versa if they perceived relative motion of the target and the accompanying dot. We reduced the size and the speed of the stimuli by half in Experiment 2 and changed the movement pattern of the target to a sine-function in Experiment 3. In Experiment 4, we presented two accompanying dots. However, the results of Experiments 1 to 4 showed no evidence that pigeons perceived relative motion. In Experiment 5, we substituted a moving frame for accompanying dots. The pigeons tended to respond to the color corresponding to the relative motion. These results suggest that pigeons may organize a set of moving objects as one object moving relative to the other in some stimulus displays in which the second object constitutes an explicit reference frame.

Human infants perceive two rods moving in concert behind an occluder as one unitary rod. In four experiments we tested whether pigeons also perceive unity of objects. Pigeons were trained on a matching-to-sample task to discriminate between one unitary rod moving at a constant speed and two aligned rods moving together at the same speed. The latter stimulus was identical to the former except for a gap in the center. In experiment 1, we tested pigeons in probe trials in which a rectangle occluded the center of the sample rods, to see which comparison stimulus, the unitary rod or the aligned two rods, the subjects would match to the sample. Two of the three subjects pecked at the two rods significantly more often than at the unitary rod. In experiment 2, we trained the same pigeons to match the sample rods moving "in front of" the occluder. Pigeons persisted in matching two separate rods to the unitary rod moving in front of the occluder. In experiments 3 and 4, we used a parallelogram and an undulating shape as the occluder to alter the shape and the size of the portions above and below the occluder by the motion of the sample rods. Both subjects chose the two rods significantly more often than chance in experiment 3 and one of them did so in experiment 4. The results suggest that pigeons do not complete occluded portions even though the two elements move in concert. These negative results suggest that some alternative way of identifying objects may have evolved in pigeons. © Springer-Verlag 2001.