Canadian journal of psychology最新文献

The modern "textbook" view of visual perception contains an inherent paradox. On the one hand, it claims that relatively simple edge-extraction processes requires a stimulus exposure of approximately 50 ms. On the other hand, it says that the identification of objects in photographs and line-drawings can be highly accurate with exposure durations as short as 100 ms. It is tempting to conclude that all the difficult work of perception occurs in the 50 ms that elapse between when these two tasks are accomplished. This article argues against this view, suggesting instead that much more than edge-extraction is accomplished by the early visual processes. To illustrate this view, a computational model is described that is capable of recovering the 3-D orientation of objects from some line-drawings, rapidly and in parallel. Data from recent visual search experiments with human observers are presented in support of this model and the implications of this view for the "textbook" view are discussed.

A common assumption is that effortless, visual texture discrimination relies on the detection of gradients between two textures. This assumption was assessed in two experiments with manipulations that smoothed (Experiment 1) or interrupted (Experiment 2) the gradient between textures comprising L- and X-type micropatterns. Compared to discrimination performance when there was an abrupt discontinuity between juxtaposed textures, performance declined moderately (about 10 percent) when the texture boundary was smoothed. In this case the two textures were asymmetrically discriminated but there was no interaction of this asymmetry with the abruptness of the texture gradient. Abrupt texture gradients, therefore, are not a necessary condition for the asymmetrical discrimination of two textures. A comparison of discrimination performance with juxtaposed textures--having an abrupt gradient--and discrimination performance when the textures were separated into distinct regions--by non-textured areas--yielded very similar results across several texture pairs. Taken together these results indicate that, in certain instances, texture discrimination may involve pattern classification-like processes that are operative in the absence of texture gradients.

The purpose of the experiments reported was to examine how novel, three-dimensional shapes are represented in long-term memory and how this might be differentially affected by monocular and binocular viewing. Three experiments were conducted. The first experiment established that slide projections of the novel objects could be recognized readily if seen in the same orientation as seen during learning. The second and third experiments examined generalization to novel depth rotations of the objects. The second experiment used slide projections of the objects. The results indicated that the representation of the objects seen during training was quite viewpoint-specific as recognition of objects in novel orientations was relatively poor. In the third experiment subjects were shown the real objects under monocular or binocular viewing. Overall, the results are consistent with a growing body of recent research showing that, at least under certain conditions, the visual system stores viewpoint-specific representations of objects.

Phenomenologically, human shape recognition appears to be invariant with changes of orientation in depth (up to parts occlusion), position in the visual field, and size. Recent versions of template theories (e.g., Ullman, 1989; Lowe, 1987) assume that these invariances are achieved through the application of transformations such as rotation, translation, and scaling of the image so that it can be matched metrically to a stored template. Presumably, such transformations would require time for their execution. We describe recent priming experiments in which the effects of a prior brief presentation of an image on its subsequent recognition are assessed. The results of these experiments indicate that the invariance is complete: The magnitude of visual priming (as distinct from name or basic level concept priming) is not affected by a change in position, size, orientation in depth, or the particular lines and vertices present in the image, as long as representations of the same components can be activated. An implemented seven layer neural network model (Hummel & Biederman, 1992) that captures these fundamental properties of human object recognition is described. Given a line drawing of an object, the model activates a viewpoint-invariant structural description of the object, specifying its parts and their interrelations. Visual priming is interpreted as a change in the connection weights for the activation of: a) cells, termed geon feature assemblies (GFAs), that conjoin the output of units that represent invariant, independent properties of a single geon and its relations (such as its type, aspect ratio, relations to other geons), or b) a change in the connection weights by which several GFAs activate a cell representing an object.

Subjects searched for the letter E in a background of Ls and Fs in displays that had 1, 2, 4, 8, or 12 letters. The letters could be shown at one of six orientations (upright or rotated clockwise in 60 degrees increments). The displays were either congruent for orientation (all letters had the same orientation) or incongruent (letters in haphazard orientations except for the target on E-present trials). Search time increased linearly with the number of letters in the display, and more so for E-absent trials than for E-present trials. Letter orientation, in general, increased search time and produced an M-shaped function. Furthermore, orientation effects were attenuated in congruent displays relative to those produced by incongruent displays. The results demonstrated systematic orientation effects on the time to search for a simple pattern embedded in simple backgrounds, and provided converging evidence for the orientation-congruency effect found by Jolicoeur (1990b, Journal of Experimental Psychology: Human Perception and Performance, 16, 351-364).

Under the assumption of a general viewpoint, particular image properties, such as cotermination, straightness, and parallelism, can be used to infer, more or less reliably, the corresponding characteristics in the world. In this paper, the literature about these nonaccidental properties (NAPs) is reviewed to trace its historical roots, to list the properties that function as NAPs, and to discuss the psychological evidence for their detection and use. Against this background, four experiments are reviewed and four are fully described that were designed to test the perceptual use of skewed symmetry (SS), which results from orthographic projection of planar bilateral or mirror symmetry (BS). Despite the large symmetry advantage obtained in all experiments, SS is only perceived as BS-in-depth in cases of closed polygons or dot patterns with higher-order types of symmetry. In all random dot patterns and in some symmetric patterns with low "Gestalt", subjects relied on more local groupings which are qualitatively affine invariant, such as clusters based on proximity or curvilinearity. Based on previous approaches in the literature and these new findings, I suggest some distinctions between different ways of using NAPs, which might foster further research.

The spontaneous or induced use of an organization strategy is examined on free recall tasks with 10-year-old children classified as rather global or rather analytical at the Group Embedded Figures test. The experimental procedure include three successive and identical tests followed by two deffered tasks, one requiring a transfer of maintenance and the other a transfer of generalization. The experimental group, who attended a simple illustration of the organization strategy before the second test, applied the strategy quickly and successfully: for these subjects, one does not note differences between global or analytical subjects in the recall performance; however, the global subjects modify their study strategy of the material on the generalization task. For the control group, global or analytical subjects have a different evolution for the performance and the strategic attitude according to the procedure. The analytical subjects are different from global subjects on the generalization task.

The origins of several phenomena of number-fact retrieval were investigated by having children in Grades 3 and 4 memorize alphaplication facts (arithmetic-like memory items composed of letters instead of numbers). Alphaplication performance paralleled memory for arithmetic facts in several important respects: Results showed (a) a large performance advantage for tie (e.g., E, E = j) over nontie problems (E, I = p), (b) that most errors involved answers from the correct alpha-table, (c) that response times and error rates were strongly correlated across problems, (d) that the correct answers to poorly learned problems tended to be the most common error responses, and (e) that performance was lower for problems introduced later in the learning sequence. Taken together, these findings support a network-interference approach (Campbell & Graham, 1985) to memory for arithmetic facts.

This study examines the interaction between the development of cognitive strategies and self-monitoring abilities in children aged 8 to 14. Children were tested individually on eight proportionality problems presented with the balance-scale task. Cognitive development was assessed by the strategy used and the performance on each problem. The indicators of self-monitoring were: latencies before and after the solution of a problem, self-evaluation of one's ability to make the balance scale stay level, proportion of oriented moves on the balance scale, and persistence on a problem. Children's self-monitoring reactions to failure were assessed by changes in strategies, verbal explanations, self-evaluation of performance, and latencies. Results showed an interaction between the complexity of the items and cognitive level. On more complex items, children of lower cognitive levels had shorter latencies, made more (but less oriented) moves on the balance scale, persisted less in their activity, and had more difficulty to evaluate properly their performance. Following failure, children of lower cognitive levels did a less accurate evaluation of their performance, modified their strategy, and did not change their verbal justification, whereas children of higher cognitive levels did a good evaluation of their performance, did not change their strategy, and had the tendency to change their verbal justification. Following failure, all children took less time planning their activity. The results suggest that self-monitoring abilities develop according to the development of cognitive strategies and are mediated by the complexity of the task.

Relationships between clinical retardation (measured by the Hamilton Depression Inventory) and selective attention (measured with a computerized version of the Stroop word colour test) were studied in a population of 21 depressed patients. Stroop interference was higher in depressed patients than in normals. Desynchronized presentations of the distractor and the target and intervals between responses and succeeding stimuli permitted depressed subjects to respectively apply and lift inhibition of the distractor so that their interference was reduced to control levels. Finally, successive inhibition scores were correlated with the retardation score in depressed subjects. The results are consistent with the hypothesis of a retardation in the application and the lifting of cognitive inhibition in depression.