Recognition by Humans and Pigeons of Novel Views of 3-D Objects and Their Photographs.

Humans and pigeons were trained to discriminate between 2 views of actual 3-D objects or their photographs. They were tested on novel views that were either within the closest rotational distance between the training views (interpolated) or outside of that range (extrapolated). When training views were 60° apart, pigeons, but not humans, recognized novel views of actual objects better than their pictures. Further, both species recognized interpolated views of both stimulus types better than extrapolated views, but a single distinctive geon enhanced recognition of novel views only for humans. When training views were 90° apart, pigeons recognized interpolated views better than extrapolated views with actual objects but not with photographs. Thus, pigeons may represent actual objects differently than their pictures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

2D observers for human 3D object recognition?

In human object recognition, converging evidence has shown that subjects' performance depends on their familiarity with an object's appearance. The extent of such dependence is a function of the inter-object similarity. The more similar the objects are, the stronger this dependence will be and the more dominant the two-dimensional (2D) image-based information will be. However, the degree to which three-dimensional (3D) model-based information is used remains an area of strong debate. Previously the authors showed that all models with independent 2D templates that allowed 2D rotations in the image plane cannot account for human performance in discriminating novel object views. Here the authors derive an analytic formulation of a Bayesian model that gives rise to the best possible performance under 2D affine transformations and demonstrate that this model cannot account for human performance in 3D object discrimination. Relative to this model, human statistical efficiency is higher for novel views than for learned views, suggesting that human observers have used some 3D structural information.     

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)     

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)     

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)     

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 comparative study of geometric rule learning by nutcrackers (Nucifraga columbiana), pigeons (Columba livia) and jackdaws (Corvus monedula).

Three avian species, a seed-caching corvid (Clark's nutcrackers; Nucifraga columbiana), a non-seed-caching corvid (jackdaws; Corvus monedula), and a non-seed-caching columbid (pigeons; Columba livia), were tested for ability to learn to find a goal halfway between 2 landmarks when distance between the landmarks varied during training. All 3 species learned, but jackdaws took much longer than either pigeons or nutcrackers. The nutcrackers searched more accurately than either pigeons or jackdaws. Both nutcrackers and pigeons showed good transfer to novel landmark arrays in which interlandmark distances were novel, but inconclusive results were obtained from jackdaws. Species differences in this spatial task appear quantitative rather than qualitative and are associated with differences in natural history rather than phylogeny. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Information and viewpoint dependence in face recognition

How we recognize faces despite rotations in depth is of great interest to psychologists, computer scientists and neurophysiologists because of the accuracy of human performance despite the intrinsic difficulty of the task. Three experiments are reported here which used three-dimensional facial surface representations to investigate the effects of rotations in depth on a face recognition task. Experiment 1, using "shape only" representations, showed that all the views used (full-face, three-quarter and profile) were equally well recognized when all had been learned. Performance was better when the same views were presented in an animated sequence rather than at random, suggesting that structure-from-motion provides useful information for recognition. When stimuli were presented inverted, performance was worse and there were differences in the recognizability of views, demonstrating that the familiarity of upright faces affects generalization across views. Experiments 2 and 3 investigated generalization from single views and found performance to be dependent on learned view. In both experiments, generalization from learned full-face fell off with increasing angle of rotation. With shape only stimuli, three-quarter views generalized well to each other, even when inverted but for profiles generalization was equally bad to all unlearned views. This difference may be explained because of the particular relationship of the profile to the axis of symmetry. In Experiment 3, addition of information about superficial properties including color and texture facilitated performance, but patterns of generalization remained substantially the same, emphasizing the importance of underlying shape information. However, generalization from the three-quarter view became viewpoint invariant and there was some evidence for better generalization between profiles. The results are interpreted as showing that three-dimensional shape information is fundamental for recognition across rotations in depth although superficial information may also be used to reduce viewpoint dependence.     

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)     

Discrimination of contour-deleted images by pigeons.

Three experiments attempted to determine which properties of pictorial representations of objects control their discrimination by pigeons. A particular focus was whether the representation mediating such discriminations could be described by the simple viewpoint-invariant primitive volumes of I. Biederman's (1987) recognition-by-components theory of object recognition or by J. Cerella's (1990) particulate features. In all 3 experiments, pigeons were first trained to discriminate drawings of 4 stimulus objects with half of the contour deleted but with the component geons postulated by Biederman's theory recoverable. Discrimination accuracy was then compared for test items containing the original particulate features, affording the retrieval of the original component geons, or having neither of these properties of the training stimuli. Although response accuracy was significantly greater when the component geons of the original objects were retrievable, measurable control over recognition by the particulate features of the objects and by their specific locations was also found. The results are consistent with the idea of component geon recognition as one of the important factors in object discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural correlates of cross-modal recognition memory by 8-month-old human infants.

Examined the neural correlates of cross-modal recognition memory in 8-mo-old infants by using ERPs. Testing began by having all Ss feel (but not see) an object for 60 sec. Test trials then followed. Infants in Condition 1 received 15 presentations of a picture of the familiar object, followed by alternating pictures of that object and a novel object. Infants in Condition 2 received 15 presentations of a picture of the novel object, followed by the same test sequence as infants in Condition 1. Infants in Condition 3 were presented with 2 test trials during which looking times were recorded to pictures of the familiar and novel objects; they then received the same test sequence as infants in Conditions 1 and 2. Infants in Condition 4 were presented only with the same test sequence as infants in Conditions 1, 2, and 3. Only in Conditions 1 and 4 was a late positive slow wave invoked by the novel object (indicative of recognition memory), although infants in Condition 3 did show a significant looking preference for the novel object. These results are contrasted with previous studies examining the neural correlates of visual recognition memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multisensory recognition of actively explored objects.

Shape recognition can be achieved through vision or touch, raising the issue of how this information is shared across modalities. Here we provide a short review of previous findings on cross-modal object recognition and we provide new empirical data on multisensory recognition of actively explored objects. It was previously shown that, similar to vision, haptic recognition of objects fixed in space is orientation specific and that cross-modal object recognition performance was relatively efficient when these views of the objects were matched across the sensory modalities (Newell, Ernst, Tjan, & Bülthoff, 2001). For actively explored (i.e., spatially unconstrained) objects, we now found a cost in cross-modal relative to within-modal recognition performance. At first, this may seem to be in contrast to findings by Newell et al. (2001). However, a detailed video analysis of the visual and haptic exploration behaviour during learning and recognition revealed that one view of the objects was predominantly explored relative to all others. Thus, active visual and haptic exploration is not balanced across object views. The cost in recognition performance across modalities for actively explored objects could be attributed to the fact that the predominantly learned object view was not appropriately matched between learning and recognition test in the cross-modal conditions. Thus, it seems that participants naturally adopt an exploration strategy during visual and haptic object learning that involves constraining the orientation of the objects. Although this strategy ensures good within-modal performance, it is not optimal for achieving the best recognition performance across modalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repetition blindness for rotated objects.

Repetition blindness (RB) is the finding that observers often miss the repetition of an item within a rapid stream of words or objects. Recent studies have shown that RB for objects is largely unaffected by variations in viewpoint between the repeated items. In 5 experiments, we tested RB under different axes of rotation, with different types of stimuli (line drawings and shaded images, intact and split), using both novel and familiar objects. Although RB was largely viewpoint invariant, in most experiments, RB was reduced for small (0°) and large (180°) viewpoint differences relative to intermediate rotations. However, these deviations from invariance were eliminated when object images were split, breaking the holistic coherence of the object. These findings suggest that RB is due mainly to the activation of object representations from local diagnostic features, but can be modulated by priming on the basis of view similarity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The pigeon's recognition of drawings of depth-rotated stimuli.

Four experiments used a 4-choice discrimination learning paradigm to explore the pigeon's recognition of line drawings of 4 objects (an airplane, a chair, a desk lamp, and a flashlight) that were rotated in depth. The pigeons reliably generalized discriminative responding to pictorial stimuli over all untrained depth rotations, despite the birds' having been trained at only a single depth orientation. These generalization gradients closely resembled those found in prior research that used other stimulus dimensions. Increasing the number of different vantage points in the training set from 1 to 3 broadened the range of generalized testing performance, with wider spacing of the training orientations more effectively broadening generalized responding. Template and geon theories of visual recognition are applied to these empirical results. (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)     

Canonical views of dynamic scenes.

The visual recognition of dynamic scenes was examined. The authors hypothesized that the notion of canonical views, which has received strong empirical support for static objects, also holds for dynamic scenes. In Experiment 1, viewpoints orthogonal to the main axis of movement in the scene were preferred over other viewpoints, whereas viewpoints in line with the main axis were least preferred. Experiment 2 provided no empirical evidence for a recognition advantage of canonical viewpoints when presented during the initial learning phase, but Experiment 3 showed a cognitive advantage for canonical viewpoints if they were presented as test stimuli during the recognition test. Overall, the findings suggest that on a phenomenological level, viewers are consciously aware of such viewpoints, and, on a cognitive level, viewers benefit from canonical viewpoints in terms of recognition accuracy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Constraints on View Combination: Effects of Self-Occlusion and Differences Among Familiar and Novel Views.

The use of multiple familiar views of objects to facilitate recognition of novel views has been addressed in a number of behavioral studies, but the results have not been conclusive. The present study was a comprehensive examination of view combination for different types of novel views (internal or external to the studied views) and different objects (amoeboid objects and objects composed of geons; objects with and without self-occlusion across rotation). The authors found that the advantage gained from the study of 2 views was more than the generalization from each of the studied views presented alone. This facilitation occurred only for internal views but not external views. In addition, the benefits from the study of 2 views diminished when (a) the studied views did not share the same visible features and when (b) the studied views were separated by a small angular difference. (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)