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Results for “Form Perception”

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PubMed1981

Effects of a secondary task on the accuracy of single aiming movements.

Recently, Schmidt, Zelaznik, and Frank and Schmidt, Zelaznik, Hawkins, Frank, and Quinn have demonstrated that in rapid, single aiming movements, variability in the movement's kinetic requirements resulted in variability in the movement's amplitude. This new explanation of the speed-accuracy trade-off in motor control, however, does not predict or explain inaccuracy for slower movements (greater than 200 msec). In the two experiments reported, we demonstrate that the Schmidt et al. model can predict variability in slow aiming movements if attention is occupied with an additional task. Subjects were required to perform single aiming movements in either 500 (Experiment 1) or 200 (Experiment 2) msec. In both experiments, the movement amplitude (30, 45, 60, and 75 cm in Experiment 1, and 10, 20, and 30 cm in Experiment 2) and the probability of an auditory probe-reaction time (RT) task were manipulated. Results indicated that only when the movement time (MT) was 500 msec did the probe-RT task change the relationship between the effective target width and the movement's average velocity. This result extended the scope of the Schmidt et al. model to movements with a duration greater than 200 msec. In addition, it seems as though slow movements are controlled by attention-demanding mental processes.

Attention↗

PubMed1989

Effects of semantic priming on visual encoding of pictures.

We investigated the effects of semantic priming on initial encoding of briefly presented pictures of objects and scenes. Pictures in four experiments were presented for varying durations and were followed immediately by a mask. In Experiments 1 and 2, pictures of simple objects were either preceded or not preceded by the object's category name (e.g., dog). In Experiment 1 we measured immediate object identification; in Experiment 2 we measured delayed old/new recognition in which targets and distractors were from the same categories. In Experiment 3 naturalistic scenes were either preceded or not preceded by the scene's category name (e.g., supermarket). We measured delayed recognition in which targets and distractors were described by the same category names. In Experiments 1-3, performance was better for primed than for unprimed pictures. Experiment 4 was similar to Experiment 2 in that we measured delayed recognition for simple objects. As in Experiments 1-3, a prime that preceded the object improved subsequent memory performance for the object. However, a prime that followed the object did not affect subsequent performance. Together, these results imply that priming leads to more efficient information acquisition. We offer a picture-processing model that accounts for these results. The model's central assumption is that knowledge of a picture's category (gist) increases the rate at which visual information is acquired from the picture.

Attention↗

PubMed1989

Sensory-perceptual qualities of images.

Four experiments demonstrated that such sensory-perceptual features of objects as weight, color, and numerosity affect imaginal performance involving images of those objects. For example, imaginary transport times of objects increased with both the hypothetical weight of the imagined object and the distance traversed. The transport functions were steeper when a map of the terrain was imagined than when it was perceived, suggesting that imaginal performance of heft did not parallel more perceptually guided performance. Corresponding to the view that images activate noncanonical information from long-term memory, mental transport times were longer for maps of familiar terrains than for those of presumably unelaborated unfamiliar terrains. Further, the effects of imaginary color discriminations depended on the familiarity of the object being imagined. Images of customarily colored familiar objects were generated faster when projected onto a surface of the same color than when projected onto a surface of another color, whereas images constructed from unfamiliar targets were recognized more accurately when the target's color differed substantially from that of the ground than when it differed by a smaller amount. The results were predicted by a model that assumed that images may incorporate ancillary characteristics in addition to canonical information.

Adult↗

PubMed1993

Implicit learning of color-word associations using a Stroop paradigm.

Our experiments asked whether implicit learning occurs for novel nonverbal associations. We presented subjects with color names printed in incongruent colors; subjects were asked to name the color in which the word was printed. In Experiment 1, each of 7 color words were associated with the same incongruent color across 6 blocks of trials, and then the color-word associations were abruptly changed. Both control subjects and patients with amnesia reduced their color-naming times across the first 6 trial blocks, and naming times increased when the color-word associations were changed. In Experiment 2, similar results were obtained when neutral words were associated with colors. In Experiment 3, we found that naming times were not disrupted when an irrelevant dimension (typecase) was changed. Finally, in Experiment 4, we found that the effect persisted across a 5-min delay. These studies provide evidence that implicit learning occurs for nonverbal associations and is independent of the brain structures damaged in amnesia.

Aged↗

PubMed1994

Dynamics of activation in long-term memory: the retrieval of verbal, pictorial, spatial, and color information.

Paivio's (1986) dual code theory was tested in 5 experiments with a new paradigm for the FAN effect that enforced genuine memory recall. Subjects had to learn associations between concepts and mediators. The FAN of the concepts in relation to the mediators was varied systematically. Response times (RT) were measured while subjects had to decide whether 2 concepts were linked to each other or not by a common mediator. In Experiment 1 the concepts and mediators were words, whereas in the other experiments the concepts were line drawings. Colors served as mediators in Experiment 2 and spatial locations served as mediators in Experiments 3, 4, and 5. All of the experiments were equivalent with respect to the FAN, the learning procedure, and the retrieval test. In all of the experiments, RT proved to be a linear function of the FAN. These results suggested that the same dynamics hold for all types of information stored in long-term memory.

Adolescent↗

PubMed1995

Object-array structure, frames of reference, and retrieval of spatial knowledge.

Experiments are reported that assessed the ability of people, without vision, to locate the positions of objects from imagined points of observation that are related to their actual position by rotational or translational components. Theoretical issues addressed were whether spatial relations stored in an object-to-object system are directly retrieved or whether retrieval is mediated by a body-centered coordinate system, and whether body-centered access involves a process of imaging updating of self-position. The results, with those of Rieser (1989), indicate that in the case of regularly structured object arrays, interobject relations are directly retrieved for the translation task, but for the rotation task, retrieval occurs by means of a body-centered coordinate system, requiring imagined body rotation. For irregularly structured arrays, access of interobject spatial structure occurs by means of a body-centered coordinate system for both translation and rotation tasks, requiring imagined body translation or rotation. Array regularity affected retrieval of spatial structure in terms of global shape of interobject relations and local object position within global shape.

Adult↗

PubMed2000

Adult age differences in task switching.

Age differences in 2 components of task-set switching speed were investigated in 118 adults aged 20 to 80 years using task-set homogeneous (e.g., AAAA ...) and task-set heterogeneous (e.g., AABBAABB ... ) blocks. General switch costs were defined as latency differences between heterogeneous and homogeneous blocks. whereas specific switch costs were defined as differences between switch and nonswitch trials within heterogeneous blocks. Both types of costs generalized over verbal, figural, and numeric stimulus materials; were more highly correlated to fluid than to crystallized abilities; and were not eliminated after 6 sessions of practice, indicating that they reflect basic and domain-general aspects of cognitive control. Most important, age-associated increments in costs were significantly greater for general than for specific switch costs, suggesting that the ability to efficiently maintain and coordinate 2 alternating task sets in working memory instead of 1 is more negatively affected by advancing age than the ability to execute the task switch itself.

Adult↗

PubMed2001

Short-term memory for duration and distance in humans: role of the hippocampus.

Control participants and hypoxic participants with bilateral hippocampal damage were tested for short-term memory (STM) for presentation duration of a single object, STM for a single object, STM for spatial distance information, and time estimation. Delays of 1, 4, 8, 12, or 16 s were used for all the STM and time estimation tests. Results indicated that relative to controls, hypoxic participants were significantly impaired for STM for duration and distance information at the long but not short delays. Similarly, time estimation was accurate only to 8 s for hypoxic participants, but STM for a single object was only mildly affected. Results suggest that the hippocampus may be required for the processing of spatial and temporal STM information.

Adolescent↗

PubMed2005

3-d interpolation in object perception: evidence from an objective performance paradigm.

Object perception requires interpolation processes that connect visible regions despite spatial gaps. Some research has suggested that interpolation may be a 3-D process, but objective performance data and evidence about the conditions leading to interpolation are needed. The authors developed an objective performance paradigm for testing 3-D interpolation and tested a new theory of 3-D contour interpolation, termed 3-D relatability. The theory indicates for a given edge which orientations and positions of other edges in space may be connected to it by interpolation. Results of 5 experiments showed that processing of orientation relations in 3-D relatable displays was superior to processing in 3-D nonrelatable displays and that these effects depended on object formation. 3-D interpolation and 3-D relatabilty are discussed in terms of their implications for computational and neural models of object perception, which have typically been based on 2-D-orientation-sensitive units.

Analysis of Variance↗

PubMed2006

On the surprising salience of curvature in grouping by proximity.

The authors conducted 3 experiments to explore the roles of curvature, density, and relative proximity in the perceptual organization of ambiguous dot patterns. To this end, they developed a new family of regular dot patterns that tend to be perceptually grouped into parallel contours, dot-sampled structured grids (DSGs). DSGs are similar to the dot lattices used to study grouping by proximity, except that only one of the potential organizations is rectilinear; the others are curvilinear. The authors used the method of M. Kubovy and J. Wagemans (1995) to study grouping by proximity in DSGs. They found that in the competition between the most likely organizations, one rectilinear and the other curvilinear, the latter is more salient. This phenomenon cannot be explained by contemporary accounts of grouping by proximity or contour integration.

Adult↗

PubMed1994

Spatial association learning by rufous hummingbirds (Selasphorus rufus): effects of relative spacing among stimuli.

Gestalt theory predicts that when cues are spatially separated from response locations, associative learning is faster when distance between cue-response location pairs is increased. This prediction was tested with 20 rufous hummingbirds (Selasphorus rufus), which learned to select rewarding feeders signaled by a spatially separated light cue in 4 treatments in which distance between cues and feeders and between cue-feeder pairs was varied. As has been shown for other animals, the hummingbirds learned more slowly when the distance between cues and feeders was increased, and as predicted by Gestalt theory, they learned faster at a given distance when distance between cue-feeder pairs was increased. This result suggests that spatial association is influenced by the proximity of other stimuli in the visual field.

Animals↗

PubMed1994

Manipulating the shape of distance effects in visual curve tracing: further evidence for the zoom lens model.

The time required to determine that two dots occur on the same curve in a visual display increases with increasing interdot curve distance. McCormick and Jolicoeur (1991) presented a model of visual curve tracing in which a local operator with a variable size receptive field tracks the curve segment intervening the two dots. In this model, human response time can be predicted by counting the number of shifts of the receptive field needed to trace the curve segment. The present study re-examined the predictive power of the zoom lens curve tracing model by selectively manipulating distractor proximity in four conditions and regressing the predictions of the model on human response time. The model was compared with two other curve tracing models, pixel by pixel tracing, and Jolicoeur, Ullman and MacKay's (1991) bipartite receptive field operator. The results provided strong support for McCormick and Jolicoeur's (1991) visual attention based zoom lens operator.

Adult↗

PubMed1965