The effect of distinctive parts on recognition of depth-rotated objects by pigeons (Columba livia) and humans.

To explore whether effects observed in human object recognition represent fundamental properties of visual perception that are general across species, the authors trained pigeons (Columba livia) and humans to discriminate between pictures of 3-dimensional objects that differed in shape. Novel pictures of the depth-rotated objects were then tested for recognition. Across conditions, the object pairs contained either 0, 1, 3, or 5 distinctive pails. Pigeons showed viewpoint dependence in all object-part conditions, and their performance declined systematically with degree of rotation from the nearest training view. Humans showed viewpoint invariance for novel rotations between the training views but viewpoint dependence for novel rotations outside the training views. For humans, but not pigeons, viewpoint dependence was weakest in the 1-part condition. The authors discuss the results in terms of structural and multiple-view models of object recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Seeing two sides at once: Effects of viewpoint and object structure on recognizing three-dimensional objects.

Five experiments demonstrated that adults can identify certain novel views of 3-dimensional model objects on the basis of knowledge of a single perspective. Geometrically irregular contour (wire) and surface (clay) objects and geometrically regular surface (pipe) objects were accurately recognized when rotated 180° about the vertical (y) axis. However, recognition accuracy was poor for all types of objects when rotated around the y-axis by 90°. Likewise, more subtle rotations in depth (i.e., 30° and 60°) induced decreases in recognition of both contour and surface objects. These results suggest that accurate recognition of objects rotated in depth by 180° may be achieved through use of information in objects' 2-dimensional bounding contours, the shapes of which remain invariant over flips in depth. Consistent with this interpretation, a final study showed that even slight rotations away from 180° cause precipitous drops in recognition accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Searching by rules: Pigeons' (Columba livia) landmark-based search according to constant bearing or constant distance.

Pigeons (Columba livia) searched for a goal location defined by a constant relative spatial relationship to 2 landmarks. For one group, landmark-to-goal bearings remained constant while distance varied. For another group, landmark-to-goal distances remained constant while direction varied. Birds were trained with 4 interlandmark distances and then tested with 5 novel interlandmark distances. Overall error magnitude was similar across groups and was larger than previously reported for Clark's nutcrackers (Nucifraga columbiana). During training, error magnitude increased with interlandmark distance for constant-bearing but not constant-distance birds. Both groups searched less accurately along the axis parallel to landmarks than along the perpendicular axis. Error magnitude increased with novel extrapolated interlandmark distances but not with novel interpolated distances. Results suggest modest geometric rule learning by pigeons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abstract-concept learning carryover effects from the initial training set in pigeons (Columba livia).

Three groups of pigeons were trained in a same/different task with 32, 64, or 1,024 color-picture stimuli. They were tested with novel transfer pictures. The training-testing cycle was repeated with training-set doublings. The 32-item group learned the same/different task as rapidly as a previous 8-item group and transferred better than the 8-item group at the 32-item training set. The 64- and 1,024-item groups learned the task only somewhat slower than other groups, but their transfer was better and equivalent to baseline performances. These results show that pigeons trained with small sets (e.g., 8 items) have carryover effects that hamper transfer when the training set is expanded. Without carryover effects (i.e., initial transfer from the 32- and 64-item groups), pigeons show the same degree of transfer as rhesus and capuchin monkeys at these same set sizes. This finding has implications for the general ability of abstract-concept learning across species with different neural architectures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of geon deletion, scrambling, and movement on picture recognition in pigeons.

E. A. Wasserman, K. Kirkpatrick-Steger, L. J. Van Hamme, and I. Biederman (1993) demonstrated that scrambling an object's parts or "geons" (I. Biederman, 1987) produced marked reductions in the pigeon's picture recognition accuracy, indicating that discriminative responding to pictures is controlled by more than simple particulate features. The present effort was designed to further assess the contribution of various stimulus attributes to picture perception. Four pigeons were trained to discriminate 4 line drawings of human-made objects. Subsequent tests revealed that (a) the spatial organization of the geons was a major contributor to picture recognition; (b) the individual geons were also important, with different pigeons demonstrating control by different subsets of geons; (c) recognition of the training drawings was positionally invariant; and (d) the points where the geons contacted one another were largely unimportant for picture recognition. The results provide further support for the notion that pigeons perceive both global and local aspects of complex stimuli in much the same way as do humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Monkeys (Macaca mulatta) learn category matching in a nonidentical same-different task.

Same–different judgments of familiar objects and animals were investigated in rhesus monkeys (Macaca mulatta) in a task based on category matches rather than identity matches. 18 categories of familiar animals and objects were each composed of 12 color slides and were presented as pairs of slides. Ss indicated "same" or "different" on a response lever for reinforcement. On Same trials, 2 different views of the same object were presented, typically with differences in perspective, lighting, and background. On Different trials, 2 pictures of different objects were presented. Ss acquired the category discriminations and transferred their response judgments accurately to novel pictures from the categories. Transfer was better to objects with which the monkeys had actually interacted rather than those with which they did not interact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transfer of a discrimination by pigeons (Columba livia) between pictured locations and the represented environments.

In Exp 1, pigeons (Columba livia) were trained in a successive slide presentation procedure to discriminate between pictures of 2 ends of a room and then trained to find food in the actual room. A congruent-transfer (CT) group learned the spatial discrimination more quickly than an incongruent-transfer (IT) group. In Exp 2's replication we used a simultaneous slide presentation procedure and added a control group. The IT group required significantly more trials than the CT or control groups. In Exp 3, order of the training conditions was reversed. CT and IT conditions had no effect on the speed of acquisition of the discrimination. This indicates that pigeons acquire a representation of spatial locations from pictures, which can then direct behavior, but the direction of transfer observed was unidirectional. This suggests that a discrimination between spatial locations may not be accurately represented in pictorial form. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concept learning at different levels of abstraction by pigeons, monkeys, and people.

Pigeon, monkey, and human subjects were trained on three two-choice picture discrimination problems that varied in level of abstraction. At the most concrete level, subjects were rewarded for choosing pictures of a single species of bird, the common kingfisher, and nonrewarded for choosing pictures of other birds. At an intermediate level of abstraction, subjects were required to discriminate bird pictures as a general category from pictures of nonbird animals. As the most abstract problem, animal pictures in general were S+ items, and nonanimal pictures were S– items. Tests with novel probe pairs of pictures in Experiment 1 indicated that human subjects rapidly mastered all three concepts. Pigeons and monkeys performed well on the concrete kingfisher problem but not on the more abstract birds and animals problems. Although this initial experiment suggested that concept learning in pigeons and monkeys might be limited to concrete categories, further training with more exemplars in Experiment 3 revealed accurate identification of animal pictures in contrast to nonanimal pictures. On the other hand, both pigeons and monkeys showed an inability to discriminate novel bird pictures from pictures of other classes of animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual behavior in pigeons: Categorization of both familiar and novel examples from four classes of natural and artificial stimuli.

Two new procedures—a four-key choice procedure and a four-ply multiple fixed ratio schedule procedure—were used to train pigeons to categorize color slides depicting natural (cat, person, flower) and human-made (car, chair) objects. In Experiments 1{a}, 1{b}, 2{a}, and 2{b}, 16 pigeons trained with 10 slides from each of four categories reliably classified novel examples from these categories. However, performance was more accurate on training than on novel stimuli. In Experiment 3, 8 pigeons learned to classify 2,000 nonrepeating slides. Thus, repetitive training with a limited number of stimuli is not necessary for pigeons to learn a four-category classification task. In Experiment 4, 4 pigeons were trained with a set of repeating slides while concurrently being trained with novel stimuli. As in Experiments 1{a}, 1{b}, 2{a}, and 2{b}, performance here was more discriminative on repeatedly seen stimuli than on novel ones. Thus, repetition facilitates categorization, whether or not the pigeons are concurrently exposed to novel stimuli. The implications of these results for models of categorization are discussed. We conclude that the conceptual abilities of pigeons are more advanced than hitherto suspected. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning of absolute and relative distance and direction from discrete visual landmarks by pigeons (Columba livia).

In an open-field search task, pigeons (Columba livia) were trained to search for a goal located at the midpoint of the hypothetical line connecting two discrete visual landmarks positioned 60 cm apart. In Experiment 1, global orienting cues were absent. After reaching training criteria, pigeons were tested with novel interlandmark distances. Search location and error on test trials suggested pigeons learned relative distance. In Experiment 2, a global orienting cue was present. After reaching training criteria, pigeons were again tested with novel interlandmark distances. Results suggested pigeons learned relative and absolute distances. In Experiment 3, pigeons searched at the midpoint of rotated arrays in both the presence and absence of an orienting cue indicating learning of relative direction. In Experiment 4, pigeons searched in the appropriate goal direction when presented with a single landmark in the presence of the orienting cue but not in its absence indicating learning of absolute direction. Results implicate a stable frame of reference as critical to spatial coding strategies and suggest pigeons are able to code location based on absolute and relative distance and direction from discrete visual landmarks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual behavior in pigeons: Categories, subcategories, and pseudocategories.

In 3 experiments with a total of 16 Ss, we explored how pigeons learn to classify diverse pictures of cats, flowers, cars, and chairs and later how they accurately categorize brand-new pictures from these classes. Using a 4-key forced-choice procedure, Ss in Exp 1 discriminated individual examples within each of the categories from one another (subcategory training); nevertheless, errors were disproportionately conceptual in nature, with Ss more likely to confuse examples within a given category than between different categories. Ss in Exp 2 trained to classify pictures into human language categories (category training) learned far faster and more completely than Ss trained to sort the same pictures into totally arbitrary groupings (pseudocategory training). Finally, in Exp 3, category-trained and subcategory-trained Ss were tested on normally oriented pictures, on left–right reversals, and on top–bottom reversals. Subcategory-trained Ss responded less accurately on both kinds of reversed pictures and less accurately on top–bottom than on left–right reversals; category-trained Ss were less affected by both types of picture reversals, only top–bottom reversals decrementing their performance. Results suggest that many words in our language denote clusters of related visual stimuli, which pigeons also see as highly similar. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Manipulating and recognizing virtual objects: Where the action is.

In an earlier report (K. L. Harman, G. K. Humphrey, and M. A. Goodale, 1999), the authors demonstrated that Os who actively rotated 3-dimensional (3-D) novel objects on a computer screen later showed faster visual recognition of these objects than did Os who had passively viewed exactly the same sequence of images of these virtual objects. In Exp 1 of the present study, using 24 18–30 yr olds, the authors show that compared to passive viewing, active exploration of 3-D object structure led to faster performance on a "mental rotation" task involving the studied objects. They also examined how much time Os concentrated on particular views during active exploration. As found in the previous report, Os spent most of their time looking at the "side" and "front" views ("plan" views) of the objects, rather than the 3-quarter or intermediate views. This preference for the plan views of an object led to the examination of the possibility in Exp 2 that restricting the studied views in active exploration to either the plan views or the intermediate views would result in differential learning. 24 18–28 yr olds were used in Exp 2. It was found that recognition of objects was faster after active exploration limited to plan views than after active exploration of intermediate views. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attending holistically versus analytically: Comparing the context sensitivity of Japanese and Americans.

Much research indicates that East Asians, more than Americans, explain events with reference to the context. The authors examined whether East Asians also attend to the context more than Americans do. In Study 1, Japanese and Americans watched animated vignettes of underwater scenes and reported the contents. In a subsequent recognition test, they were shown previously seen objects as well as new objects, either in their original setting or in novel settings, and then were asked to judge whether they had seen the objects. Study 2 replicated the recognition task using photographs of wildlife. The results showed that the Japanese (a) made more statements about contextual information and relationships than Americans did and (b) recognized previously seen objects more accurately when they saw them in their original settings rather than in the novel settings, whereas this manipulation had relatively little effect on Americans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rotational object discrimination by pigeons.

Four experiments examined the discrimination of directional object motion by pigeons. Four pigeons were tested in a go/no-go procedure with video stimuli of geons rotating right or left around their central y-axis. This directional discrimination was learned in 7 to 12 sessions and was not affected by changes in object starting orientation, but did require the coherent ordering of the videos’ successive frames. Subsequent experiments found no or little transfer of this motion discrimination to novel objects. Experiments varying the speed of rotation and degrees of apparent motion per frame revealed that both factors strongly affected the discrimination. Finally, tests with partial occlusion of different portions of a rotating object suggested that the majority of the object was likely involved in determining rotational direction. These experiments indicate that pigeons can exclusively use motion cues to judge relative object motion. They also suggest the pigeons may have used a specific representation of the motion sequences of each object to make the discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pigeon same–different concept learning with multiple stimulus classes.

Two experiments examined the acquisition and transfer of a complex same–different discrimination by pigeons. With the use of a 2-alternative choice task, 5 pigeons were reinforced for discriminating odd-item Different displays, in which a contrasting target was present, from Same displays, in which all elements were identical. Four different types of same-different displays were concurrently tested. The display types differed in their configuration (texture vs. visual search organization), the nature of their elements (small and large colored shapes; pictures of birds, flowers, fish, and humans), and the processing demands required by their global-local element arrangement. Despite these differences, the pigeons learned to discriminate all 4 display types at the same rate and showed positive discrimination transfer to novel examples of each type, suggesting that a single generalized rule was used to discriminate all display types. These results provide some of the strongest evidence yet that pigeons, like many primates, can learn an abstract, visually mediated same-different concept. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus mode and concept formation in preschool children.

Examined effects of stimulus mode (objects vs pictures) on the acquisition, generalization, and transfer of novel concepts. 65 preschoolers were taught animal- and machine-like concepts and then given generalization and recognition tests. On these tests, item mode was either consistent or inconsistent with training mode (object–object, object–picture, picture–object, picture–picture). Neither training nor recognition was affected by stimulus mode. On generalization, however, modality interacted with training mode and level of elaboration. At low elaboration levels, generalization was less for objects than for pictures and was depressed by object training. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of the effects of depth rotation on visual and haptic three-dimensional object recognition.

A sequential matching task was used to compare how the difficulty of shape discrimination influences the achievement of object constancy for depth rotations across haptic and visual object recognition. Stimuli were nameable, 3-dimensional plastic models of familiar objects (e.g., bed, chair) and morphs midway between these endpoint shapes (e.g., a bed–chair morph). The 2 objects presented on a trial were either both placed at the same orientation or were rotated by 90° relative to each other. Discrimination difficulty was increased by presenting more similarly shaped objects on mismatch trials (easy: bed, then lizard; medium: bed, then chair; hard: bed, then bed–chair morph). For within-modal visual matching, orientation changes were most disruptive when shape discrimination was hardest. This interaction for 3-dimensional objects replicated the interaction reported in earlier studies presenting 2-dimensional pictures of the same objects (Lawson & Bülthoff, 2008). In contrast, orientation changes and discrimination difficulty had additive effects on within-modal haptic and cross-modal visual-to-haptic matching, whereas cross-modal haptic-to-visual matching was orientation invariant. These results suggest that the cause of orientation sensitivity may differ for visual and haptic object recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition by diazepam of the effect of additional training and of extinction on the retention of shuttle avoidance behavior in rats.

Rats were submitted to a training and a test session in a shuttle avoidance task. In some groups, a second training session was interpolated 2 or 24 hr after the first session. In others, a session of extinction was interpolated 2 or 24 hr after the training session. When the interpolated task was 2 hr after training, training-test interval was 24 hr. When the interpolated task was 24 hr after training, training-test interval was 48 hr. The additional training enhanced, and the extinction depressed, retention test performance. Diazepam, given 30 min prior to the first (or only) training session enhanced the performance of avoidance responses in that session but inhibited it in the subsequent retention test. Diazepam given 90 min after training had no effect on retention. Diazepam given 30 min prior to either the additional training session or the extinction session did not affect performance in that session but canceled their effects on retention test performance. The effects are related to the previously described prevention by diazepam of interfering effects on memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Seeing things from a different angle: The pigeon's recognition of single geons rotated in depth.

In 2 experiments involving computer-rendered versions of single shapes or "geons," the extent to which depth rotation affects the visual discrimination performance of pigeons in both go/no-go and forced-choice tasks was documented. The pigeons were able to recognize geons at most rotations in depth; however, the pigeons' recognition performance was better at the training view than at most other views. Aspects of these results are both consistent with and problematic for object-centered and viewer-centered theories of object recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)