Object Recognition under Sequential Viewing Conditions: Evidence for Viewpoint-Specific Recognition Procedures

Perception ◽  
1994 ◽  
Vol 23 (5) ◽  
pp. 595-613 ◽  
Author(s):  
Rebecca Lawson ◽  
Glyn W Humphreys ◽  
Derrick G Watson
Keyword(s):  
Object Recognition ◽  
Primary Role ◽  
Object Knowledge ◽  
Line Drawings ◽  
Efficient Access ◽  
Neurophysiological Studies ◽  
Specific Object ◽  
Depth Rotation ◽  
Series Of Experiments ◽  
Image Descriptions

In many computational approaches to vision it has been emphasised that object recognition involves the encoding of view-independent descriptions prior to matching to a stored object model, thus enabling objects to be identified across different retinal projections. In contrast, neurophysiological studies suggest that image descriptions are matched to less abstract, view-specific representations, resulting in more efficient access to stored object knowledge for objects presented from a view similar to a stored viewpoint. Evidence favouring a primary role for view-specific object descriptions in object recognition is reported. In a series of experiments employing line drawings of familiar objects, the effects of depth rotation upon the efficiency of object recognition were investigated. Subjects were required to identify an object from a sequence of very briefly presented pictures. The results suggested that object recognition is based upon the matching of image descriptions to view-specific stored representations, and that priming effects under sequential viewing conditions are strongly influenced by the visual similarity of different views of objects.

Contrast Sensitivity in Human Visual Areas and Its Relationship to Object Recognition

2002 ◽  
Vol 87 (6) ◽  
pp. 3102-3116 ◽  
Author(s):  
Galia Avidan ◽  
Michal Harel ◽  
Talma Hendler ◽  
Dafna Ben-Bashat ◽  
Ehud Zohary ◽  
...  
Keyword(s):  
Object Recognition ◽  
High Sensitivity ◽  
Ventral Stream ◽  
High Order ◽  
Object Representations ◽  
Lateral Occipital Complex ◽  
Line Drawings ◽  
Visual Areas ◽  
The Face ◽  
Contrast Invariance

An important characteristic of visual perception is the fact that object recognition is largely immune to changes in viewing conditions. This invariance is obtained within a sequence of ventral stream visual areas beginning in area V1 and ending in high order occipito-temporal object areas (the lateral occipital complex, LOC). Here we studied whether this transformation could be observed in the contrast response of these areas. Subjects were presented with line drawings of common objects and faces in five different contrast levels (0, 4, 6, 10, and 100%). Our results show that indeed there was a gradual trend of increasing contrast invariance moving from area V1, which manifested high sensitivity to contrast changes, to the LOC, which showed a significantly higher degree of invariance at suprathreshold contrasts (from 10 to 100%). The trend toward increased invariance could be observed for both face and object images; however, it was more complete for the face images, while object images still manifested substantial sensitivity to contrast changes. Control experiments ruled out the involvement of attention effects or hemodynamic “ceiling” in producing the contrast invariance. The transition from V1 to LOC was gradual with areas along the ventral stream becoming increasingly contrast-invariant. These results further stress the hierarchical and gradual nature of the transition from early retinotopic areas to high order ones, in the build-up of abstract object representations.

The Role of Attention on Viewpoint-Invariant Object Recognition

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 148-148
Author(s):  
B J Stankiewicz ◽  
J E Hummel
Keyword(s):  
Object Recognition ◽  
Shape Representation ◽  
Invariant Representation ◽  
Shape Constancy ◽  
Priming Paradigm ◽  
Human Object ◽  
Invariant Object Recognition ◽  
Series Of Experiments ◽  
Invariant Representations

Researchers in the field of visual perception have dedicated a great deal of effort to understanding how humans recognise known objects from novel viewpoints (often referred to as shape constancy). This research has produced a variety of theories—some that emphasise the use of invariant representations, others that emphasise alignment processes used in conjunction with viewpoint-specific representations. Although researchers disagree on the specifics of the representations and processes used during human object recognition, most agree that achieving shape constancy is computationally expensive—that is, it requires work. If it is assumed that attention provides the necessary resources for these computations, these theories suggest that recognition with attention should be qualitatively different from recognition without attention. Specifically, recognition with attention should be more invariant with viewpoint than recognition without attention. We recently reported a series of experiments, in which we used a response-time priming paradigm in which attention and viewpoint were manipulated, that showed attention is necessary for generating a representation of shape that is invariant with left-right reflection. We are now reporting new experiments showing that shape representation activated without attention is not completely view-specific. These experiments demonstrate that the automatic shape representation is invariant with the size and location of an image in the visual field. The results are reported in the context of a recent model proposed by Hummel and Stankiewicz ( Attention and Performance16 in press), as well as in the context of other models of human object recognition that make explicit predictions about the role of attention in generating a viewpoint-invariant representation of object shape.

How ”Implicit\ Are Implicit Color Effects in Memory?

2002 ◽  
Vol 49 (2) ◽  
pp. 120-131 ◽  
Author(s):  
Hubert D. Zimmer ◽  
Astrid Steiner ◽  
Ullrich K. H. Ecker
Keyword(s):  
Episodic Memory ◽  
Implicit Memory ◽  
Choice Test ◽  
Study Phase ◽  
Implicit Test ◽  
Color Information ◽  
Explicit Test ◽  
Line Drawings ◽  
Memory Traces ◽  
Specific Object

Abstract. Processing colored pictures of objects results in a preference to choose the former color for a specific object in a subsequent color choice test ( Wippich & Mecklenbräuker, 1998 ). We tested whether this implicit memory effect is independent of performances in episodic color recollection (recognition). In the study phase of Experiment 1, the color of line drawings was either named or its appropriateness was judged. We found only weak implicit memory effects for categorical color information. In Experiment 2, silhouettes were colored by subjects during the study phase. Performances in both the implicit and the explicit test were good. Selections of ”old\ colors in the implicit test, though, were almost completely confined to items for which the color was also remembered explicitly. In Experiment 3, we applied the opposition technique in order to check whether we could find any implicit effects regarding items for which no explicit color recollection was possible. This was not the case. We therefore draw the conclusion that implicit color preference effects are not independent of explicit recollection, and that they are probably based on the same episodic memory traces that are used in explicit tests.

Measurement and Modelling of Perceived Slant in Surfaces Represented by Freely Viewed Line Drawings

Perception ◽  
1998 ◽  
Vol 27 (5) ◽  
pp. 505-540 ◽  
Author(s):  
Roddy Cowie
Keyword(s):  
Individual Differences ◽  
General Rule ◽  
Surface Orientation ◽  
Picture Perception ◽  
Distinctive Character ◽  
Line Drawings ◽  
Series Of Experiments ◽  
Anchor Points

Simple pictures under everyday viewing conditions evoke impressions of surfaces oriented in depth. These impressions have been studied by measuring the slants of perceived surfaces, with probes (rotating arrowheads) designed to respect the distinctive character of depicted scenes. Converging arguments indicated that the perceived orientation of the probes was near theoretical values. A series of experiments showed that subjects formed well-defined impressions of depicted surface orientation. The literature suggests that perceived objects might be ‘flattened’, but that was not the general rule. Instead, both mean slant and uncertainty fitted models in which slant estimates are derived in a relatively straightforward way from local relations in the picture. Simplifying pictures tended to make orientation estimates less certain, particularly away from the natural anchor points (vertical and horizontal). The shape of the object affected all aspects of the observed-object/percept relationship. Individual differences were large, and suggest that different individuals used different relationships as a basis for their estimates. Overall, data suggest that everyday picture perception is strongly selective and weakly integrative. In particular, depicted slant is estimated by finding a picture feature which will be strongly related to it if the object contains a particular regularity, not by additive integration of evidence from multiple directly and indirectly relevant sources.

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