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At least 811 records · Page 45Linked to original sources
PubMed2006

Contributions of invariants, heuristics, and exemplars to the visual perception of relative mass.

Some potential contributions of invariants, heuristics, and exemplars to the perception of dynamic properties in the colliding balls task were explored. On each trial, an observer is asked to determine the heavier of 2 colliding balls. The invariant approach assumes that people can learn to detect complex visual patterns that reliably specify which ball is heavier. The heuristic approach assumes that observers only have access to simple motion cues. The exemplar-based approach assumes that people store particular exemplars of collisions in memory, which are later retrieved to perform the task. Mathematical models of these theories are contrasted in 2 experiments. Observers may use more than 1 strategy to determine relative mass. Although observers can learn to detect and use invariants, they may rely on either heuristics before the invariant has been learned or exemplars when memory demands and similarity relations allow.

Biomechanical Phenomena↗
PubMed1977

Auditory and visual perception of simultaneous verbal and nonverbal stimuli.

In an auditory experiment, digits and tonal sequences were presented simultaneously to both ears. In a visual experiment, words and nonsense figures had to be compared in both visual half-fields. The verbral stimuli were better reported from the right ear and right visual half-field. The nonverbal stimuli were reported equally well from both ears and visual half-fields. It appears that the processing of stimuli presented to both input channels depends on the type of the stimuli. These results point to a cerebral mechanism classifying incoming information to the brain and yielding an optimal processing of verbal and nonverbal stimuli by the cerebral hemispheres.

Acoustic Stimulation↗
PubMed1998

Higher order and lower order variables in the visual perception of relative pulling force.

In 7 experiments, undergraduates judged the force exerted by a videotaped standing puller, a computer-generated (stick-figure) puller, or a computer-generated inverted pendulum. Single and stepwise multiple regression analyses determined the kinematic variables exploited by the participants. Results show that (a) judgments correlated highly with force and improved with feedback; (b) judgments correlated more highly with lower order kinematic variables than with force itself; (c) participants differed in the kinematic variables exploited; (d) participants changed over blocks of trials in the variables exploited; (e) some participants used compound kinematic variables; (f) the variables exploited depended on the type of feedback; and (g) judgments to upright pullers, inverted pullers, and simple pendula showed the same qualitative patterns. Implications for theories of direct perception, directed perception, and heuristics are considered.

Adult↗
PubMed2003

Spatial localization precedes temporal determination in visual perception.

The temporal order of two spots of light successively appearing in the dark, just before a saccade, influences their perceived spatial relation. Both spots are mislocalized in the saccade direction--the second more so than the first--because mislocalization grows as time elapses from stimulus to saccade onset. On the other hand, the perceived order of the two spots may be altered if the second spot is at the focus of spatial attention. How would these illusory perceptions of space and time interact when they are brought to play together? Could they be independent or could one perception depend on the other? Here we show that perceived location of stimuli is not affected by illusory temporal order, whereas perceived temporal order is affected by misperceived location. The results suggest that the brain processes spatial location of visual stimuli before processing their temporal order.

Attention↗
PubMed1981

Unconscious and conscious processes during visual perception.

Ongoing unconscious processes may be influenced by related conscious processes without self-awareness. (a) When the conscious semantic interpretation of physically identical shapes changes due to their angular rotation, the sequence of saccadic movements arid the localization of eye fixations over the shapes change as well. (b) The amplitude of the P 300 wave of visual evoked potentials is related to the conscious cognitive interpretation of identical stimuli. (c) The instants of figure reversals are influenced by conscious cognitive programs delineated by means of corresponding experimental instructions. It is assumed that unconscious and conscious processes may be considered functional manifestations of the same complex and specific neuronal network at different levels of its hierarchical organization and that mutual interactions between both types of processes do not require the existence of any mediating "interface" system.

Awareness↗
PubMed2005

When visual perception causes feeling: enhanced cross-modal processing in grapheme-color synesthesia.

In synesthesia, stimulation of one sensory modality (e.g., hearing) triggers a percept in another, non-stimulated sensory modality (e.g., vision). Likewise, perception of a form (e.g., a letter) may induce a color percept (i.e., grapheme-color synesthesia). To date, the neural mechanisms underlying synesthesia remain to be elucidated. We disclosed by fMRI, while controlling for surface color processing, enhanced activity in the left intraparietal cortex during the experience of grapheme-color synesthesia (n = 9). In contrast, the perception of surface color per se activated the color centers in the fusiform gyrus bilaterally. The data support theoretical accounts that grapheme-color synesthesia may originate from enhanced cross-modal binding of form and color. A mismatch of surface color and grapheme induced synesthetically felt color additionally activated the left dorsolateral prefrontal cortex (DLPFC). This suggests that cognitive control processes become active to resolve the perceptual conflict resulting from synesthesia.

Acoustic Stimulation↗