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PubMed1988

Overflow, first-sight, and vanishing point distances in visual imagery.

The relationship between the size of a familiar object and the distances at which it is imaged is examined in three experiments. The distance at which an imaged object overflows the visual field is linearly related to object size, a result consistent with the size-distance invariance hypothesis (Kosslyn, 1980). The distance at which an object is initially imaged, first-sight distance, is related to the object size by a power function with an exponent less than 1. In addition, time required to scan from the first-sight to the overflow distance increases as a function of the difference between the two distance estimates. The distance at which an imaged object becomes too small to be identified, vanishing point distance, is related to object size by a power function with an exponent less than 1. This result does not support predictions made from the size-distance invariance hypothesis or Kosslyn's model of visual imagery. Implications for a theory of visual imagery and memory are discussed.

Adult↗

PubMed1989

Wide-angle memories of close-up scenes.

We report a picture-memory phenomenon in which subjects' recall and recognition of photographed scenes reveal a pronounced extension of the pictures' boundaries. After viewing 20 pictures for 15 s each, 37 undergraduates exhibited this striking distortion; 95% of their drawings included information that had not been physically present but that would have been likely to have existed just outside the camera's field of view (Experiment 1). To determine if boundary extension is limited to recall and drawing ability, Experiment 2 tested recognition memory for boundaries. Eighty-five undergraduates rated targets and distractors on a boundary-placement scale. Subjects rated target pictures as being closer up than before and frequently mistook extended-boundary distractors as targets. Results are discussed in terms of picture comprehension and memory. In addition to its theoretical value, discovery of the phenomenon demonstrates the importance of more widespread use of open-ended tests in picture-memory methodology.

Adult↗

PubMed1989

Subjective hierarchies in spatial memory.

Two experiments investigated the structure of spatial memories. Subjects learned locations of objects in spatial layouts (Experiment 1) or locations of object names on maps (Experiment 2). Physical and perceptual boundaries were absent in these spatial arrays. Subjects then participated in three tasks: item recognition, in which the variable of interest was spatial priming; free and cued recall; and Euclidean distance estimation. Ordered-tree analysis of individual subjects' recall protocols produced hierarchical trees consistent with regularities in output order. Spatial priming and distance estimations depended on whether pairs of objects appeared in the same subtree or in different subtrees. These findings indicate that spatial memories have a hierarchical component, even when physical and perceptual boundaries are nonexistent. Priming also increased with depth of clustering in ordered trees. This result supports spreading-activation theories of retrieval but provides evidence against several "non-spreading-activation" theories.

Adult↗

PubMed1982

Effect of task demands on dual coding of pictorial stimuli.

Recent studies have suggested that verbal labeling of a picture does not occur automatically. Although several experiments using paired-associate tasks produced little evidence indicating the use of a verbal code with picture stimuli, the tasks were probably not sensitive to whether the codes were activated initially. It is possible that verbal labels were activated at input, but not used later in performing the tasks. The present experiment used a color-naming interference task in order to assess, with a more sensitive measure, the amount of verbal coding occurring in response to word or picture input. Subjects named the color of ink in which words were printed following either word or picture input. If verbal labeling of the input occurs, then latency of color naming should increase when the input item and color-naming word are related. The results provided substantial evidence of such verbal activation when the input items were words. However, the presence of verbal activation with picture input was a function of task demands. Activation occurred when a recall memory test was used, but not when a recognition memory test was used. The results support the conclusion that name information (labels) need not be activated during presentation of visual stimuli.

Attention↗

PubMed1994

Toward a general theory of stereopsis: binocular matching, occluding contours, and fusion.

Models of stereopsis have focused on developing strategies for identifying common features in the 2 half-images so that disparity may be computed. This emphasis ignores the unpairable features that arise at occluding contours (half-occlusions). Most models treat half-occlusions as noise or outliers that are interpreted after disparity processing is completed. A series of experiments reveal that occlusion relationships are sensed during the earliest stages of binocular processing. The authors hypothesize the existence of receptive field structures that sense the local structure of stereoscopic occlusion relationships to account for these findings. Finally, a simple theoretical framework is presented in which fusion, stereopsis, and occlusion are unified. This theory explains the co-occurrence of stereopsis and diplopia and how half-occlusions escape the suppression characteristic of binocular rivalry.

Contrast Sensitivity↗

PubMed1994

A neural theory of attentive visual search: interactions of boundary, surface, spatial, and object representations.

Visual search data are given a unified quantitative explanation by a model of how spatial maps in the parietal cortex and object recognition categories in the inferotemporal cortex deploy attentional resources as they reciprocally interact with visual representations in the prestriate cortex. The model visual representations are organized into multiple boundary and surface representations. Visual search in the model is initiated by organizing multiple items that lie within a given boundary or surface representation into a candidate search grouping. These items are compared with object recognition categories to test for matches or mismatches. Mismatches can trigger deeper searches and recursive selection of new groupings until a target object is identified. The model provides an alternative to Feature Integration and Guided Search models.

Algorithms↗

PubMed2006

What do we learn from binding features? Evidence for multilevel feature integration.

Four experiments were conducted to investigate the relationship between the binding of visual features (as measured by their aftereffects on subsequent binding) and the learning of feature-conjunction probabilities. Both binding and learning effects were obtained, but they did not interact. Interestingly, (shape-color) binding effects disappeared with increasing practice, presumably because of the fact that only 1 of the features involved was relevant to the task. However, this instability was only observed for arbitrary, not highly overlearned combinations of simple geometric features and not for real objects (colored pictures of a banana and strawberry), where binding effects were strong and resistant to practice. These findings suggest that learning has no direct impact on the strength or resistance of bindings or on speed with which features are bound; however, learning does affect the amount of attention particular feature dimensions attract, which again can influence which features are considered in binding.

Analysis of Variance↗

PubMed1990

Implicit memory for unfamiliar objects depends on access to structural descriptions.

We investigated implicit memory for unfamiliar objects with a task in which subjects decided whether structurally possible and impossible line drawings could exist in three-dimensional space. In Experiment 1, significant priming effects on object decision performance were observed after encoding of global, three-dimensional object structure but not local, two-dimensional object features. Explicit memory did not differ significantly as a function of global vs. local study processing. In Experiments 2 and 3, elaborative encoding had different effects on object decision and recognition performance, thus providing evidence for functional dissociation between implicit and explicit memory. Stochastic independence between object decision and recognition performance was also observed. Results were consistent with the hypothesis that implicit memory, as indexed by priming on the object decision task, depends on encoding of and access to structural descriptions of objects.

Attention↗

PubMed1967