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I Rock

Publications and source records attributed to I Rock.

At least 19 recordsLinked to original sources
PubMed2001

Location and attention.

A discrepancy exists in the literature concerning attention and visual localization accuracy. Prinzmetal, Amiri, Allen, and Edwards (1998), and Tsal and Bareket (1999a) found that localization accuracy increases with attention. Using an inattention paradigm, Rock, Linnett, Grant, and Mack (1992) found no difference between localization accuracy in three attention conditions: inattention, divided attention, and control. Using a similar inattention paradigm, the current study addressed this discrepancy. Subjects were instructed to perform a line judgement task, and attention for an additional location task was manipulated. In Experiment 1, location accuracy was worse in the inattention condition than in either the divided-attention or the control condition. There was no difference between the divided-attention and control conditions. Experiment 2 controlled for the possibility that improved location accuracy in the divided and control conditions was due to the expectation of performing a location response, rather than the manipulation of attention. Our results are in agreement with previous findings (Prinzmetal et al., 1998; Tsal & Bareket, 1999a) and suggest that the apparent discrepancy is due to coarse coding of the location responses in the study by Rock et al. (1992).

Adolescent↗
PubMed1998

Inattentional blindness as a function of proximity to the focus of attention.

The effect of the distance between the center of the focus of attention and an unexpected stimulus on detection was examined in two experiments with the use of the inattentional-blindness paradigm [Mack and Rock, 1998 Inattentional Blindness (Cambridge, MA: MIT Press)]. In experiment 1, the closer a stimulus was to the center of attention, the more likely it was to be detected. Experiment 2 replicated this finding and controlled for retinal eccentricity. These results suggest that low-level stimulus characteristics (e.g. location) may play an important role in the detection of unexpected stimuli. The data are consistent with previous research on the spatial aspects of attention demonstrating that the distance to the focus of attention is a critical variable. This study demonstrates that the effect of distance is similar under conditions of inattention. Theories put forward to explain inattentional blindness should include 'early' attentional factors, as well as factors resulting from later stages of processing.

Adolescent↗
PubMed1997

A belongingness principle of motion perception.

Four experiments are reported that investigated the role of the perceived coplanarity of a moving target with respect to a frame of reference in the third dimension on the perceived path of that target. When a target dot and small moving frame appeared coplanar, the dot's perceived trajectory was governed entirely by its changing position relative to the moving frame. However, when the target and a large stationary frame appeared in a different plane than the small moving frame, the motion of the dot was seen independently of the moving frame. The results support a belongingness principle of motion perception: The displacement of an object relative to a frame of reference to which it belongs governs its perceived path of motion.

Adult↗
PubMed1995

Retinal vs. environmental orientation in the perception of the right angle.

The right angle is perceived as such only when its sides are vertical and horizontal (Goldmeier effect). We investigated if spontaneous verbal descriptions reflect this type of "oblique effect", and if the relevant frame of reference is retinal or environmental. We compared four conditions in which upright vs. tilted observers were asked to describe gravitationally normal vs. oblique angles. It is shown that the Goldmeier effect depends upon the environmental coordinates, which usually determine the orientation of the subjective frame of reference. We argue that the singularity of the right angle in the vertical/horizontal orientation depends on a phenomenological fact: only the normal right angle looks like a right angle.

Discrimination, Psychological↗
PubMed1995

Level of processing in the perception of symmetrical forms viewed from different angles.

This study is concerned with the level of processing underlying the perception of symmetry about a vertical axis. Specifically, it asks whether the equality of the two sides of a symmetrical pattern must be present retinally or perceptually for the impression of symmetry to be realized. Sixty-four subjects were assigned to groups that viewed symmetrical and asymmetrical figures when the figures were in either a frontoparallel plane or one slanted by 65 deg from the line of sight. In the 65 deg condition, the objectively symmetrical stimuli projected an asymmetrical shape on the retina, and conversely the objectively asymmetrical stimuli produced a symmetrical retinal projection. From each viewing angle, patterns were observed under either full or reduced (monocular) depth cue conditions. Like their counterparts in the frontoparallel condition, observers in the 65 deg, full depth-cue condition identified the objective symmetry of the figures. By contrast, 65 deg, reduced depth-cue observers responded primarily to the retinal structure of the stimuli. The same pattern of responding was observed for both holistic and multielement patterns and for both 100 ms and 1 s exposures. These findings and the significant relationship obtained between phenomenal judgment of symmetry and a measure of shape constancy suggest that the perception of symmetrical figures depends upon the perception of the equality of their two halves, and is thus another example of perceptual causality.

Adolescent↗
PubMed1994

Why do ambiguous figures reverse?

For much of this century the dominant theory of reversal of ambiguous figures has been neural satiation. We suggest a very different kind of theory based on the consequences of the typical instructions given to subjects in experiments on reversal. In analyzing these instructions in preliminary experiments we conclude that what matters is the subject's knowledge that the figure is reversible and specific knowledge of how its alternative construals appear. This leads to an intention to reverse the figure. In one experiment we demonstrate that recent experience with the ambiguous figure and its two modes of appearance does not lead to its reversal if the subject does not know the figure is reversible. In another experiment we demonstrate that when the subject does know the ambiguous figure is reversible, it nonetheless will not tend to reverse if the intention to do so is contravened by a different intention. We suggest that the intention to reverse cannot succeed unless the subject "knows" how to carry it out and, further, that the intention may become involuntary and automatic.

Female↗
PubMed1994

Do young children reverse ambiguous figures?

Most adult observers tend not to reverse ambiguous figures if they are not informed about the ambiguity of the figure. The question was asked whether very young children who have rarely, if ever, seen any kinds of ambiguous figures will reverse if uninformed, and also how they will behave if they are informed. It was found that 3 and 4 year olds never reverse when presented with two different kinds of ambiguous figures when uninformed, and only some do even when informed; further, those that do reverse do so only once or twice over a 60 s inspection period. These results are interpreted as further confirmation of an earlier finding with adults--that reversal is not simply a matter of prolonged inspection of an ambiguous figure leading automatically to neural satiation. Instead, cognitive factors such as utilization of memory and intention are implicated.

Attention↗
PubMed1994

The dependence of two-dimensional shape perception on orientation.

While it is true that in daily life we generally recognize objects regardless of their orientation, previous experiments involving novel shapes indicate a decline in recognition when these are tested in altered orientation. Here the question is raised of whether there is a component of shape perception based purely on the geometry of an object, independent of orientation. By means of two tests designed to eliminate awareness of change of orientation, one more stringent than used heretofore, it was found that shape perception is dependent on orientation. The apparent contradiction between these findings and the apparent orientation-free character of recognition in daily life is discussed.

Female↗
PubMed1993

Is a perceived shape based on its retinal image?

Although the processing of phenomenal shape might be supposed to begin at an early stage, with the shape of the retinal image of an object, it is possible that it does not begin until a later stage at which the locations of the parts of the object have been perceived. Such perceived locations are based on a compensation or constancy mechanism that takes account of eye position. Ordinarily these two possible bases of shape perception--retinal image and perceived location--are confounded. To separate them the parts of a shape were presented sequentially, during which time the eyes were in motion. The eye movement did not alter phenomenal locations of the parts vis-à-vis one another but did yield an entirely different composite retinal image of the parts. Another method employed was to change the location of each sequentially presented part with respect to a displacing frame of reference. By and large the results indicate that the composite shape perceived is based on the perceived location of the parts of the object with respect to one another, rather than on the composite retinal image.

Adult↗
PubMed1992

Perceptual organization and attention.

It is widely assumed that the grouping of the visual field first described by the Gestalt psychologists and the related phenomenon of texture segregation occur very early in the processing of visual information and involve preattentive processes. All the recent evidence supporting this assumption comes from visual search experiments in which the subject is actively looking for a target and attending to the stimulus. The question at issue is whether these kinds of patterns are perceived under conditions of inattention, i.e., when observers are not searching for them. We performed six experiments to determine whether texture segregation and grouping by similarity or proximity are perceived under conditions of inattention. On the first two trials subjects were asked to report the longer arm of a briefly presented cross which was surrounded by a pattern of ungrouped small elements. On the third trial and subsequent control trials these elements were configured into grouping patterns and subjects queried about them immediately following their line length reports. The results establish that neither texture segregation nor grouping by similarity of lightness or proximity are perceived under conditions of inattention. They support the conclusion that there is an earlier stage of processing than that referred to as preattentive.

Adult↗
PubMed1992

Perception without attention: results of a new method.

Having found by the use of a new method for examining perception without attention that grouping and texture segregation do not seem to occur (see Mack, Tang, Tuma, Kahn, & Rock (1992) Cognitive Psychology, 24, we go on to ask what is perceived without attention using this new method. Our subjects receive only one inattention trial in a sequence of trials involving a visual distraction task. In addition to the distraction task in the inattention trial, subjects received a stimulus of which they had no prior knowledge or expectation and were questioned or tested directly afterward for their perception of that stimulus. Two subsequent trials containing test stimuli serve as within-subject controls. The results of a series of experiments indicate that the presence of one or more stimulus objects and their locations are preattentively perceived, as is their color, but shape is not. Because individual items are detected without attention, we conclude that perceptual organization is initially based on a principle in which connected regions of uniform stimulation are inferred to be discrete units (the principle of uniform connectedness). One striking, unexpected finding is that without attention many subjects have no awareness at all of the stimulus object, an effect we call inattentional blindness.

Attention↗
PubMed1992

Stereokinetic effect and its relation to the kinetic depth effect.

The stereokinetic effect (SKE) has been defined and studied by nested circular patterns rotating on a turntable. Circles must appear not to rotate as they revolve, which in turn results in their appearing to translate relative to one another. A powerful illusion of object depth results even though the individual circles do not undergo an appropriate foreshortening consistent with their apparent changes in slant. It is suggested and tested that the SKE is based on the changing positions between the nested contours despite the absence of any change within each contour, whereas the kinetic depth effect (KDE) entails both kinds of change. It follows that a turntable method of presentation is not necessary, and between-contour transformations can be simulated by computer animation. Displays consisting of simple translations were shown to evoke robust depth impressions as were patterns consisting of contours of varying shapes. Comparisons of the depth, compellingness, and rigidity of matched SKE and KDE displays are reported. The SKE is taken to be paradigmatic for how the visual system perceives depth when observing small object rotations that occur in everyday situations.

Depth Perception↗
PubMed1992

Further evidence of failure of reversal of ambiguous figures by uninformed subjects.

In studying the reversal of ambiguous figures investigators understandably have always informed subjects of the reversibility of the figures and of how each version appears. However, such knowledge may be a cause of reversal and is therefore an undesirable aspect of the method used to study it. An experiment is described that is an improvement in some respects on a previously reported one in which subjects are not informed about reversal. The result was that only about a third of the subjects ever reversed. In a control condition the same subjects were informed in the traditional way and then not only did they always reverse but did so very frequently in the time period tested. Theoretical implications of these findings are discussed.

Attention↗
PubMed1992

Grouping based on phenomenal similarity of achromatic color.

It is widely acknowledged that a precondition for the perception of the world of objects and events is an early process of organization, and it has generally been assumed that such organization is based on the Gestalt laws of grouping. However, the stage at which such grouping occurs, whether early or late, is an empirical question. It is demonstrated in two experiments that grouping by similarity of neutral color is based not on similarity of absolute luminance at the level of the proximal stimulus, but on phenomenal similarity of lightness resulting from the achievement of lightness constancy. An alternative explanation of such grouping based on the equivalence of luminance ratios between elements and background is ruled out by appropriate control conditions.

Adult↗
PubMed1990

Illusory contours from pictorially three-dimensional inducing elements.

Illusory-figure patterns which are composed of pictorial elements representing three-dimensional partial disks are sometimes effective and sometimes not. When they are not effective, it is apparently because they contain information that contradicts the presence of an occluding figure and/or because all of the edges within the pattern are seen as edges of various pictured surfaces of the elements.

Attention↗
PubMed1989

Can we imagine how objects look from other viewpoints?

Many psychologists who study cognition believe that perception achieves object-centered representations that make it possible to extract representations of how the object would appear from differing viewpoints. Others believe we can achieve representations of how an object would appear by a process of visualization or mental rotation. We report experiments in which the subject tries to imagine how three-dimensional novel wire objects would appear from positions other than the one they are in. Subjects are unable to perform this task unless they make use of strategies that circumvent the process of visualization. It is suggested that the linear increase in time required to succeed in mental rotation tasks as a function of the angular discrepancy between the figures compared is the result of increasing difficulty rather than of the time required for rotation.

Adult↗
PubMed1989

Regression to egocentrically determined description of form under conditions of inattention.

Although, ordinarily, upright objects are readily recognized by observers who are tilted, it is hypothesized that this is achieved by a process of correction. The first stage of that process is held to be a description of the object in relation to the biologically more primitive system of retinal coordinates. In order to test this hypothesis, tilted subjects were required to view figures under conditions of inattention (Experiment 1) or divided attention (Experiment 2). Under such conditions description may not proceed beyond that first stage. The results showed that recognition was higher for figures that maintained their orientation with respect to the retina (although they were then tilted in the environment) than for figures that remained upright in the environment (although they were then disoriented with respect to the retina). This outcome is the very opposite of what occurs under conditions of attention.

Adult↗