Accelerated behavioural development changes fine-scale search behaviour and spatial memory in honey bees (Apis mellifera L.).

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.

The learning of basic-level categories by pigeons: the prototype effect, attention, and effects of categorization.

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.

Investigation of object-based attention in pigeons (Columba livia) and hill mynas (Gracula religiosa) using a spatial cueing task.

In previous research, pigeons and hill mynas that performed differently on an object permanence task were presumed to attend to objects in different ways (Plowright, Reid, & Kilian, 1998). In the current study, we conducted 4 experiments to investigate if the attention of hill mynas and pigeons is object-based and if there are species differences in their visual-attentional processes. In Experiment 1, pigeons were tested in a spatial cueing task requiring them to respond sequentially to a cue and a target that appeared at 1 of the 4 ends of two rectangles. Both when the response to a fixation stimulus was required before target presentation (Experiment 1A) and when such a response was not required (Experiment 1B), there were no significant differences in reaction times to the targets appearing at cued and noncued rectangles; these results provided no evidence of object-based attention in pigeons. In Experiment 2, for 2 of the 3 hill mynas tested in a procedure similar to that for the pigeons in Experiment 1B, reaction times were shorter to the target appearing on the cued rectangle than to the target appearing on noncued rectangle, suggesting the operation of object-based attention, as in humans. In Experiment 3, we tested naive pigeons by means of the procedure used for hill mynas in Experiment 2. However, again pigeons showed no evidence of object-based attention, suggesting a species difference in attentional processes. The generality of the current results and evolution of the possible species differences were discussed. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Pigeons discriminate shapes based on topological features.

The use of topological features in visual recognition has been demonstrated only in species with global-cue precedence. We investigated whether pigeons, with local-cue precedence, use topological features as cues for discriminating different shapes. The subjects in the topology group were required to discriminate stimuli based on whether the shapes contained one or no holes, whereas the subjects in the pseudocategory group were required to discriminate stimuli based on arbitrary categories. In contrast to the pseudocategory group, which showed little improvement in stimuli discrimination over the sessions, the topology group showed rapid improvement, indicating that the latter group performed better than what was expected from rote learning. Moreover, our data suggest that shape discrimination in pigeons is based on on-off feature information contained in the stimuli. We conclude that certain species with local-cue precedence are capable of perceiving topological features and that this type of perception may be a primitive component of the visual system.

Use of redundant sets of landmark information by humans (Homo sapiens) in a goal-searching task in an open field and on a computer screen.

Landmark-based goal-searching tasks that were similar to those for pigeons (Ushitani & 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. (PsycINFO Database Record

Rapid visual processing of picture stimuli by pigeons in an RSVP (rapid serial visual presentation) task.

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. (PsycINFO Database Record

Perception of the standard and the reversed Müller-Lyer figures in pigeons (Columba livia) and humans (Homo sapiens).

The authors compared perception of the standard and reversed Müller-Lyer figures between pigeons (Columbia livia) and humans (Homo sapiens). In Experiment 1, pigeons learned to classify 6 lengths of target lines into "long" and "short" categories by pecking 2 keys on the monitor, ignoring the 2 brackets so placed that they would not induce an illusion. In the test that followed, all 3 birds chose the "long" key more frequently for the standard Müller-Lyer figures with inward-pointing brackets (><) than for the figures with outward-pointing brackets (<>). The subjects' responses were accountable by neither overall lengths of the figures nor horizontal gaps between the 2 brackets. For the reversed figures, effects of the brackets were absent. These results suggested that the pigeons perceived the standard Müller-Lyer illusion but not the reversed one. Experiment 2 confirmed that humans perceived both types of the illusion. Pigeons and humans may perceive the same illusory figures in different ways.

Performance of pigeons (Columba livia) on maze problems presented on the LCD screen: in search for preplanning ability in an avian species.

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.

Better living by not completing: a wonderful peculiarity of pigeon vision?

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.

Pigeons do not perceptually complete partly occluded photos of food: an ecological approach to the "pigeon problem".

Humans routinely complete partly occluded objects to recognize the whole objects. However, a number of studies using geometrical figures and even conspecific images have shown that pigeons fail to do so. In the present study, we tested whether pigeons complete partially occluded objects in a situation simulating a natural feeding context. In Experiment 1, we trained pigeons to peck at any photograph of food and not to peck at any containing a non-food object. At test, we presented both photos of food partly occluded by pigeon's feather and photos simply truncated at the same part. We predicted that if the pigeons perceptually completed the occluded portion, then they would discriminate the photos of occluded food better than the truncated photos. The result was that the pigeons pecked at the truncated photos earlier than the occluded photos. Placing the occluder next to all of the stimuli in Experiment 2 or substituting indented lozenge for the feather in Experiment 3 did not affect the results. Thus, even in a simulated ecologically significant situation, pigeons continued to not show evidence of perceptual completion.

Infant monkeys' concept of animacy: the role of eyes and fluffiness.

Both human and nonhuman primates have been suggested to possess some essential knowledge about animate entities, but it remains unclear whether the concept of animacy is shared across species, which properties are used as an "animacy marker," and whether such ability is present at birth. We investigated infant Japanese monkeys' looking responses towards novel objects varying in both physical appearance and self-propelled motion, with the aim of depicting the role of eyes and fluffiness in the early recognition of animacy. Presented with an inanimate natural stone, three-month-old monkeys showed longer looking times at the stone's self-propelled motion than at its baseline still posture. This effect became significantly smaller when artificial fur was attached to the stone, while adding artificial eyes did not elicit a departing pattern in their looking behavior. In contrast, one-month-old monkeys showed no systematic differences in their looking behavior. This suggests that the concept of animacy in terms of self-propelledness may develop between one and three months of age, with sensitivity to texture emerging by three months. Development of biological knowledge is discussed in relation to social knowledge from both ontogenetic and phylogenetic perspectives.

Flexible learning and use of multiple-landmark information by pigeons (Columba livia) in a touch screen-based goal searching task.

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.

A slowing effect on visual search by advance information in pigeons (Columba livia): a comparison with humans (Homo sapiens).

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.

Object-based attention in chimpanzees (Pan troglodytes).

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.