Priming contour-deleted images: evidence for intermediate representations in visual object recognition

The speed and accuracy of perceptual recognition of a briefly presented picture of an object is facilitated by its prior presentation. Picture priming tasks were used to assess whether the facilitation is a function of the repetition of: (a) the object's image features (viz., vertices and edges), (b) the object model (e.g., that it is a grand piano), or (c) a representation intermediate between (a) and (b) consisting of convex or singly concave components of the object, roughly corresponding to the object's parts. Subjects viewed pictures with half their contour removed by deleting either (a) every other image feature from each part, or (b) half the components. On a second (primed) block of trials, subjects saw: (a) the identical image that they viewed on the first block, (b) the complement which had the missing contours, or (c) a same name-different exemplar of the object class (e.g., a grand piano when an upright piano had been shown on the first block). With deletion of features, speed and accuracy of naming identical and complementary images were equivalent, indicating that none of the priming could be attributed to the features actually present in the image. Performance with both types of image enjoyed an advantage over that with the different exemplars, establishing that the priming was visual rather than verbal or conceptual. With deletion of the components, performance with identical images was much better than that with their complements. The latter were equivalent to the different exemplars, indicating that all the visual priming of an image of an object is through the activation of a representation of its components in specified relations. In terms of a recent neural net implementation of object recognition (Hummel & Biederman, in press), the results suggest that the locus of object priming may be at changes in the weight matrix for a geon assembly layer, where units have self-organized to represent combinations of convex or singly concave components (or geons) and their attributes (e.g., aspect ratio, orientation, and relations with other geons such as TOP-OF). The results of these experiments provide evidence for the psychological reality of intermediate representations in real-time visual object recognition.     

Lateralized effects of categorical and coordinate spatial processing of component parts on the recognition of 3D non-nameable objects

Participants performed two object-matching tasks for novel, non-nameable objects consisting of geons. For each original stimulus, two transformations were applied to create comparison stimuli. In the categorical transformation, a geon connected to geon A was moved to geon B. In the coordinate transformation, a geon connected to geon A was moved to a different position on geon A. The Categorical task consisted of the original and the categorically transformed objects. The Coordinate task consisted of the original and the coordinately transformed objects. The original object was presented to the central visual field, followed by a comparison object presented to the right or left visual half-fields (RVF and LVF). The results showed an RVF advantage for the Categorical task and an LVF advantage for the Coordinate task. The possibility that categorical and coordinate spatial processing subsystems would be basic computational elements for between- and within-category object recognition was discussed.     

Priming and Recognition of Human Motion Patterns

Left-right orientation and size incongruence is known to affect recognition memory for objects but not object priming. In the present study, the effects of study-test changes in left-right orientation and size on old-new recognition decisions and long-term priming of human motion patterns were examined. Experiment 1 showed effects of orientation incongruence on both recognition and priming. Experiment 2 showed an effectof size incongruence on recognition memory but not on priming. It is suggested that the representations of human actions that underlie human motion priming are on a level that preserve orientation, possibly because of the importance of dynamic information for perceiving motion patterns or because encoding of human motion is governed by a body schema (e.g. Reed & Farah, 1995). In contrast, low-level metric information such as size is inconsequential to priming because priming involves identification of shape, which is not affected by size transformations. The effect of size on recognition memory, on the other hand, shows thatexplicitrecognition decisions may draw on any available episodic information, including metric attributes, to make an old new discrimination.     

"What is my avatar seeing?": The coordination of "out-of-body" and "embodied" perspectives for scene recognition across views

Scene recognition across a perspective change typically exhibits viewpoint dependence. Accordingly, the more the orientation of the test viewpoint departs from that of the study viewpoint, the more time its takes and the less accurate observers are to recognize the spatial layout. Three experiments show that observers can take advantage of a virtual avatar that specifies their future “embodied” perspective on the visual scene. This “out-of-body” priming reduces or even abolishes viewpoint dependence for detecting a change in an object location when the environment is respectively unknown or familiar to the observer. Viewpoint dependence occurs when both the priming and primed viewpoints do not match. Changes to permanent extended structures (such as walls) or altered object-to-object spatial relations across viewpoint change are detrimental to viewpoint priming. A neurocognitive model describes the coordination of “out-of-body” and “embodied” perspectives relevant to social perception when understanding what another individual sees.     

Orientation invariance in visual object priming depends on prime—target asynchrony

Two experiments are reported in which orientation effects on visual object recognition latency were examined. In Experiment 1, we assessed picture-naming performance as a function of image-plane stimulus orientation and found increasing response times with increased misorientation of the stimulus. In Experiment 2, we examined the repetition priming effect on the identification of upright targets as a function of prime orientation. With time delays of 100, 200, or 500 msec between the onset of the prime and that of the target (i.e., stimulus onset asynchrony [SOA]), the magnitude of the priming effect decreased with increasing misorientation of the prime. These results contrast with the orientationinvariant priming effects reported in some previous repetition priming studies. These investigations all used relatively long prime—target SOAs. Confirming the crucial role of the latter variable, Experiment 2 shows that the magnitude of the repetition priming effect is invariant across prime orientations with an SOA of 1,000 msec. The possible implications of the present observations with respect to the issue of orientation invariance versus dependency of the visual object recognition process are discussed.     

Orientation invariance in visual object priming depends on prime-target asynchrony

Two experiments are reported in which orientation effects on visual object recognition latency were examined. In Experiment 1, we assessed picture-naming performance as a function of image-plane stimulus orientation and found increasing response times with increased misorientation of the stimulus. In Experiment 2, we examined the repetition priming effect on the identification of upright targets as a function of prime orientation. With time delays of 100, 200, or 500 msec between the onset of the prime and that of the target (i.e., stimulus onset asynchrony [SOA]), the magnitude of the priming effect decreased with increasing misorientation of the prime. These results contrast with the orientation-invariant priming effects reported in some previous repetition priming studies. These investigations all used relatively long prime-target SOAs. Confirming the crucial role of the latter variable, Experiment 2 shows that the magnitude of the repetition priming effect is invariant across prime orientations with an SOA of 1,000 msec. The possible implications of the present observations with respect to the issue of orientation invariance versus dependency of the visual object recognition processare discussed.     

Long-term retinotopic priming in object identification

An important result in perception research is that priming in an object naming task is invariant with translation and left-right reflection. A more sensitive object recognition paradigm was used in three experiments in order to investigate the extent to which priming of object identification is affected by changes in left-right orientation and position. In a prime phase, participants viewed consecutively presented object images. In a subsequent probe phase, participants identified familiar objects in rapid visual streams of nonobject distractors. In Experiment 1, images previously viewed in the same left-right orientation were primed more than images previously viewed in the opposite orientation (i.e., a left-right reflection). This reflection-sensitive priming was replicated in Experiment 2 using a brief (300-msec) prime exposure. In Experiment 3, when the retinal locations of prime and probe images matched, reflection-sensitive priming was also obtained, but when the retinal locations of prime and probe images differed, no reflection-sensitive priming was observed. These results suggest that a single prime exposure can produce long-term priming that is sensitive to left-right reflection, but that this priming is specific to a retinal location.     

Electrophysiological evidence for size invariance in masked picture repetition priming

This experiment examined invariance in object representations through measuring event-related potentials (ERPs) to pictures in a masked repetition priming paradigm. Pairs of pictures were presented where the prime was either the same size or half the size of the target object and the target was either presented in a normal orientation or was a normal sized mirror reflection of the prime object. Previous masked repetition priming studies have found a cascade of priming effect sensitive to perceptual (N190/P190) and semantic (N400) properties of the stimulus. This experiment found that both early (N190/P190 effects) and later effects (N400) were invariant to size, whereas only the N190/P190 effect was invariant to mirror reflection. The combination of a small prime and a mirror reflected target led to no significant priming effects. Taken together, the results of this set of experiments suggests that object recognition, more specifically, activating an object representation, occurs in a hierarchical fashion where overlapping perceptual information between the prime and target is necessary, although not always sufficient, to activate a higher level semantic representation.     

A mere exposure effect for transformed three-dimensional objects: Effects of reflection, size, or color changes on affect and recognition

If the mere exposure effect is based on implicit memory, recognition and affect judgments should be dissociated by experimental variables in the same manner as other explicit and implicit measures. Consistent with results from recognition and picture naming or object decision priming tasks (e.g., Biederman & E. E. Cooper, 1991, 1992; L. A. Cooper, Schacter, Ballesteros, & Moore, 1992), the present research showed that recognition memory but not affective preference was impaired by reflection or size transformations of three-dimensional objects between study and test. Stimulus color transformations had no effect on either measure. These results indicate that representations that support recognition memory code spatial information about an object’s left-right orientation and size, whereas representations that underlie affective preference do not. Insensitivity to surface feature changes that do not alter object form appears to be a general characteristic of implicit memory measures, including the affective preference task.     

Achieving visual object constancy across plane rotation and depth rotation.

Visual object constancy is the ability to recognise an object from its image despite variation in the image when the object is viewed from different angles. I describe research which probes the human visual system's ability to achieve object constancy across plane rotation and depth rotation. I focus on the ecologically important case of recognising familiar objects, although the recognition of novel objects is also discussed. Cognitive neuropsychological studies of patients with specific deficits in achieving object constancy are reviewed, in addition to studies which test neurally intact subjects. In certain cases, the recognition of invariant features allows objects to be recognised irrespective of the view depicted, particularly if small, distinctive sets of objects are presented repeatedly. In contrast, in most situations, recognition is sensitive to both the view in-plane and in-depth from which an object is depicted. This result suggests that multiple, view-specific, stored representations of familiar objects are accessed in everyday, entry-level visual recognition, or that transformations such as mental rotation or interpolation are used to transform between retinal images of objects and view-specific, stored representations.     

The priming of face recognition after metric transformations

Four experiments were performed to test whether the perceptual priming of face recognition would show invariance to changes in size, position, reflectional orientation (mirror reversal), and picture-plane rotation. In all experiments, subjects recognized faces in two blocks of trials; in the second block, some of the faces were identical to those in the first, and others had undergone metric transformations. The results show that subjects were equally fast to recognize faces whether or not the faces had changed in size, position, or reflectional orientation between the first and second presentations of the faces. In contrast, subjects were slower to recognize both faces and objects when they were planar-rotated between the first and second presentations. The results suggest that the same metric invariances are shown by both face recognition and basic-level object recognition.     

Evidence for complete translational and reflectional invariance in visual object priming.

The magnitude of priming on naming reaction times and on the error rates, resulting from the perception of a briefly presented picture of an object approximately 7 min before the primed object, was found to be independent of whether the primed object was originally viewed in the same hemifield, left-right or upper-lower, or in the same left-right orientation. Performance for same-name, different-examplar images was worse than for identical images, indicating that not only was there priming from block one to block two, but that some of the priming was visual, rather than purely verbal or conceptual. These results provide evidence for complete translational and reflectional invariance in the representation of objects for purposes of visual recognition. Explicit recognition memory for position and orientation was above chance, suggesting that the representation of objects for recognition is independent of the representations of the location and left-right orientation of objects in space.     

Repetition priming and the haptic recognition of familiar and unfamiliar objects

In four experiments, we examined the haptic recognition of 3-D objects. In Experiment 1, blindfolded participants named everyday objects presented haptically in two blocks. There was significant priming of naming, but no cost of an object changing orientation between blocks. However, typical orientations of objects were recognized more quickly than nonstandard orientations. In Experiment 2, participants accurately performed an unannounced test of memory for orientation. The lack of orientation-specific priming in Experiment 1, therefore, was not because participants could not remember the orientation at which they had first felt an object. In Experiment 3, we examined haptic naming of objects that were primed either haptically or visually. Haptic priming was greater than visual priming, although significant cross-modal priming was also observed. In Experiment 4, we tested recognition memory for familiar and unfamiliar objects using an old-new recognition task. Objects were recognized best when they were presented in the same orientation in both blocks, suggesting that haptic object recognition is orientation sensitive. Photographs of the unfamiliar objects may be downloaded from www.psychonomic.org/archive.     

ONE-SHOT VIEW INVARIANCE IN A MOVING WORLD

Abstract— How do people recognize an object in a novel orientation? Psychophysical and neurophvsiological studies have suggested that extensive practice is required before observers can recognize an object that has been rotated to a new orientation Because object orientation frequently vanes with object movement, we examined whether observers might more readily recognize a moving object in a new orientation Results from a priming study indicate that motion significantly arid readily enhances the recognition of new object orientations when those orientations fait within the path of the motion That is motion promotes view-invariant object recognition without practice     

Orientation-specific possibility priming for novel three-dimensional objects.

Priming effects on the object possibility task, in which participants decide whether line drawings could or could not be possible three-dimensional objects, may be supported by the same processes and representations used in recognizing and identifying objects. Three experiments manipulating objects' picture-plane orientation provided limited support for this hypothesis. Like old/new recognition performance, possibility priming declined as study-test orientation differences increased from 0 degree to 60 degrees. However, while significant possibility priming was not observed for larger orientation differences, recognition performance continued to decline following 60 degrees-180 degrees orientation shifts. These results suggest that possibility priming and old/new recognition may rely on common viewpoint-specific representations but that access to these representations in the possibility test occurs only when study and test views are sufficiently similar (i.e., rotated less than 60 degrees).     

Orientation-specific possibility priming for novel three-dimensional objects

Priming effects on the object possibility task, in which participants decide whether line drawings could or could not be possible three-dimensional objects, may be supported by the same processes and representations used in recognizing and identifying objects. Three experiments manipulating objects’ picture-plane orientation provided limited support for this hypothesis. Like old/new recognition performance, possibility priming declined as study-test orientation differences increased from 0° to 60°. However, while significant possibility priming was not observed for larger orientation differences, recognition performance continued to decline following 60°–180° orientation shifts. These results suggest that possibility priming and old/new recognition may rely on common viewpoint-specific representations but that access to these representations in the possibility test occurs only when study and test views are sufficiently similar (i.e., rotated less than 60°).     

Determinants of spatial priming in environmental memory

Spatial priming in recognizing objects in experimentally learned environments has been proposed as strong evidence for spatial organization of environmental memory. However, in all studies showing recognition priming effects, encoding and rehearsal contiguity may have coincided with spatial proximity, and thus priming may have been due to temporal associations formed during rehearsal, not encoded spatial relations per se. We investigated this question in four experiments, using a trip trial learning method in which temporal contiguity and spatial relations were independent. In Experiment 1, no spatial priming in recognition was found, even though indirect evidence suggested that subjects had encoded spatial relations. In Experiment 2, the trip trial method was compared with the free study procedure commonly used in previous priming studies. Spatial priming occurred only for free study subjects, even though the two groups were equivalent on direct measures of encoding accuracy. In Experiment 3, spatial priming in recognition was obtained with a modification of the trip trial method in which temporal and spatial contiguity were deliberately confounded. In Experiment 4, the unmodified trip trial method produced spatial priming in a location-decision task. Taken together, our results suggest that environmental memory may be spatially organized, but retrieval of object identities does not necessarily activate encoded spatial relations.