Change in visual memory following discrimination learning.

Studied visual recognition memory for the size of circles for evidence of active memory change in 3 experiments with 34 paid volunteers and 83 undergraduates. In Exp. I the remembered difference in size between 2 circles which had been discriminated on the basis of size increased, while the remembered difference in size between the same 2 circles discriminated on the basis of brightness did not. In Exp. II, the remembered size of the smallest of 4 circles discriminated by size changed from 1 day to 1 wk. Each S in Exp. III inspected either 1 or 2 circles and was asked to remember their size. There was more memory distortion when 2 circles were remembered, but the distortion did not change over time. The evidence suggests that memory will actively change after a visual discrimination task. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory-based automaticity in the discrimination of visual numerosity.

In the development of memory-based models of automaticity, it is crucial to specify the nature of the memory representation. Seven experiments with 94 students use a counting task to determine whether a feature (i.e., identity, color, or orientation) is explicitly represented in memory. It is assumed that the degree of transfer to a pattern differing on one feature is determined by that feature's importance in supporting skilled performance. Exp 1 determined the practice necessary to obtain automaticity. In Exps 2a, 3a, and 4a, which investigated the nature of the representation after extended practice, changing neither the identity nor color of elements had strong effects on transfer, but changing pattern orientation did impair memory retrieval, thus suggesting that for the counting task, pattern orientation is more important than element identity or color. Exps 2b, 3b, and 4b replicated these results after limited practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decision processes in visual discrimination of line orientation.

The contribution of decision factors to the meridional variations in line orientation discrimination (OD) was determined for 2-alternative forced-choice experimental designs. With K. O. Johnson's (1980) formalization of decision processes in discrimination tasks, 3 decision factors were identified: decision rule, memory variance, and criterial noise. Exp I (with 13 Ss) showed the effect of experimental design on OD to be similar at horizontal and oblique standard orientations, indicating that the meridional variations in OD were not due to a decision rule anisotropy. In Exp II (with 5 Ss) the effect of the interstimulus interval was also found to be similar at both standard orientations, suggesting that the memory variance is isotropic in the orientation domain. Exps III and IV (with a total of 7 Ss) supported the hypothesis that the meridional variations in OD are not due to a criterial noise anisotropy. Results strongly suggest that the oblique effect in OD is due to sensorial factors rather than to decision factors. Therefore, they further support the hypothesis linking the anisotropy of the preferred orientation distribution of Area 17-S cells (a single physiologically defined class of cells in the primary visual cortex) and the meridional variations in OD. (58 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactivation of a visual discrimination in early infancy.

16 78–92 day old infants learned to produce movement in 2 successively presented overhead crib mobiles by footkicking in a conjugate reinforcement paradigm. The mobiles differed in both color and pattern displays on the suspended components. Following acquisition, a discrimination was introduced whereby responding was reinforced in the presence of one mobile (the positive stimulus; S+) but not in the presence of the other (the negative stimulus; S–). During a cued-recall retention test administered 21 days after the completion of discrimination training, Ss evidenced no retention of either initial or discrimination training. Nevertheless, a brief reactivation treatment with S+ 24 hrs prior to the long-term retention test alleviated forgetting and restored the S+/S– discrimination. Reactivation with S– was no more effective than no reactivation treatment at all. Results confirm the efficacy of reminder procedures with young infants and demonstrate the specificity with which the reminder alleviates forgetting. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Order of processing in visual perception.

Three experiments tested predictions derived from 3 cognitive scanning hypotheses proposing respectively a left-to-right, ends-first, and peripheral-foveal order of scanning. In Exps I and II configurations of letters and/or digits were presented to 11 Ss around a central fixation point, and the stimulus was followed by a 1-sec presentation of a patterned mask or a blank white field. Backward masking selectively impaired the identification of stimuli in foveal positions whether or not these stimuli occupied middle-of-row positions. In Exp III 4 Ss made a manual same-different response to the presence or absence of a critical letter presented 3Deg. to the left or right of fixation. Noise letters appeared on either side or both sides of the critical letter. Identification response times were faster when the critical letter appeared in the left-most position in left field arrays and the right-most position in right field arrays. Principal conclusions drawn from the 3 experiments were: (a) Alphanumeric stimuli are scanned from the peripheral visual field inward towards fixation. (b) Any left-to-right scanning occurs relatively late in iconic processing. (c) An ends-first scanning strategy is a particular case of a more general peripheral-foveal strategy. (French summary) (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lack of power enhances visual perceptual discrimination.

Powerless individuals face much challenge and uncertainty. As a consequence, they are highly vigilant and closely scrutinize their social environments. The aim of the present research was to determine whether these qualities enhance performance in more basic cognitive tasks involving simple visual feature discrimination. To test this hypothesis, participants performed a series of perceptual matching and search tasks involving colour, texture, and size discrimination. As predicted, those primed with powerlessness generated shorter reaction times and made fewer eye movements than either powerful or control participants. The results indicate that the heightened vigilance shown by powerless individuals is associated with an advantage in performing simple types of psychophysical discrimination. These findings highlight, for the first time, an underlying competency in perceptual cognition that sets powerless individuals above their powerful counterparts, an advantage that may reflect functional adaptation to the environmental challenge and uncertainty that they face. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effect of psychopathology on visual discrimination.

"Perceptual and motor aspects of the Bender-Gestalt Test performance were compared for 4 groups of Ss: 10 student nurses, 10 acute schizophrenic patients, 10 chronic schizophrenic patients, and 10 patients hospitalized for neurological reasons… . After the Ss had obtained equal experiences with the Bender designs by reproducing them under memory and copy conditions, a perceptual multiple-choice test was administered under memory and matching conditions. Results indicate that there are marked differences in perceptual accuracy between the 4 groups: the control population was most accurate, with the acute schizophrenic, chronic schizophrenic, and neurological patients less proficient in that order." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in visual recall memory following discrimination learning.

Trained 100 undergraduates to discriminate among 4 visual stimuli on either 1 of the 2 dimensions which differentiated them: area (large or small circles) or dot density (thickly or lightly filled with dots). Recall was tested immediately or after delay of 4 hrs, 1 day, 1 wk, or 2 wks by having each S draw all 4 stimuli at 1 of these intervals. Differences in recall along the dimension which was discriminated were exaggerated relative to differences on the other dimension. The relative exaggeration was large immediately following testing, declined to a minimum after 1 wk, and increased again after 2 wks. Results are consistent with previously reported changes in visual recognition memory, and suggest a 2-process interpretation. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Location confusions in visual information processing.

Tested in 2 experiments, using 21 undergraduates, the location-confusion model proposed by P. Dixon (see record 1986-21077-001) to account for interference that occurs when deciding whether a briefly presented target item appeared in a briefly presented array. The model assumed that information about the location of items decayed quickly and that Ss sometimes had difficulty deciding whether a particular identity code corresponded to the target or the array. Exp 1 confirmed the assumption that the interference only occurred with visual targets. Exp 2 tested for interference at the level of identity codes for well-learned vs arbitrary visual patterns (AVPs). No interference from AVPs on accuracy was observed. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parrel processing in visual short-term memory.

Visual short-term memory for the contrast and spatial frequency of sinusoidal gratings was measured in a delayed discrimination task in which the 2 stimuli to be compared were separated in time by 1-10 s interstimulus intervals (ISIs). Delayed discrimination thresholds for spatial frequency and contrast were compared, both when the 2 types of thresholds were measured in separate blocks of trials and when the 2 types of measures were randomly intermixed in an uncertainty paradigm, which required participants to process information about both dimensions on each trial. In both cases, accuracy of memory for spatial frequency was independent of ISI, but memory for contrast decreased as ISI increased. Performance was lower in the uncertainty case, but only by an amount predicted by statistical decision theory for independent sources. The results are consistent with a model assuming a set of parallel special-purpose visual discrimination and short-term memory mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Familiarity effects in visual information processing.

Reviews the literature and deals, predominantly, with the issue of whether familiarity aids in the extraction of visual features or in the interpretation, either verbal or visual, of the features extracted. Familiar visual objects, such as normal letters and real words, are processed faster and more accurately than are unfamiliar objects. This fact is massively documented by a wide variety of studies, involving tachistoscopic recognition, visual comparison, and letter detection. Less clear is how and where familiarity has its effect. There actually appear to be several familiarity effects, some aiding the extraction and/or interpretation of visual information, others aiding nonperceptual processes (e.g., storing and reporting or comparing the information). (31/2 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parallel pattern processing and visual agnosia.

Conducted 3 visual-search experiments to examine parallel pattern processing in a man with visual agnosia, who suffered a stroke at age 61 yrs. The authors examined "search for targets" as defined by (1) the combination of features relative to homogeneous distractors, (2) the combination of features relative to heterogeneous distractors, and (3) a single feature difference relative to the distractors. The patient's performance was compared with that of 2 control groups: 10 young (aged 20–36 yrs) and 6 age-matched non-brain damaged controls (aged 63–68 yrs). The patient showed normal search functions for single-feature targets and for combined-feature targets among heterogeneous distractors. The relations between the patient's agnosia and his problem in the parallel grouping of form conjunctions are discussed. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Capacity limitations in visual word processing.

The ability of subjects to process English words in a spatially parallel manner was examined in several redundant-target detection tasks. When redundant targets were identical in a given display, processing limitations were evident in a task that required subjects to make semantic categorizations of words. However, parallel processing of identical redundant target words was exhibited in a lexical decision task that required a structural analysis of letter strings, but not an analysis of word meaning. The difference in performance in the two tasks suggests that the capacity for semantic processing is limited. Analyses designed to examine whether the redundancy gain in Experiment 2 could be attributed to limited capacity processing in conjunction with positional preferences provided evidence against this possibility. In addition, these analyses suggested that the processing times for the redundant targets in Experiment 2 might be positively correlated. In the third and fourth experiments, the redundant-target displays contained two different words. Processing interference, in the form of a redundancy loss, was evident in the lexical decision task, but not in the semantic categorization task, confirming a difference in the mode of processing between the two tasks. The results provide evidence against the unlimited-capacity, parallel processing hypothesis of late selection theories of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electroencephalographic correlates of delayed-alternation and visual discrimination learning in rhesus monkeys.

Trained 4 female monkeys on a 5-sec delayed-alternation (DA) task and on a simultaneous visual discrimination task. An EEG was recorded through chronically implanted electrodes from dorsolateral frontal cortex (sulcus principalis), inferotemporal cortex, and caudate nucleus. Prestimulus and preresponse EEG amplitudes and frequencies were analyzed for 3 levels of performance for each task. For both frontal and caudate placements: (a) on the DA task, prestimulus voltage was highest at the intermediate performance level, and the inverted- shape was statistically significant; (b) there was a significant task difference for the prestimulus but not for the preresponse, interval. For the inferotemporal placement a significant task difference was found for preresponse, but not for prestimulus, amplitudes. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Size in the visual processing of faces and words.

Three experiments, with 34 right-handed university students, studied the influence of variations of stimulus size upon recognition of words and faces. Ss viewed a series of 640 slides of words of faces presented in 1 of 5 sizes and responded as to whether or not stimulus had been previously presented. Size played an important role in the recognition of faces but was irrelevant to the recognition of words. Analysis revealed that although irrelevant to recognition, size of words was nevertheless encoded, with some consequences similar to those for recognition of faces. The likelihood of recognition declined linearly with the numbers of words intervening between a word and its recurrence, while the likelihood of recognizing a face declined exponentially in the same circumstances. Results are interpreted in terms of stimulus-specific analyses, and this view is contrasted with other notions of mental representation. Variant measures are appended. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic processing of non-attended visual information.

In 2 experiments, with 28 university students, reaction time (RT) to name 1 of 2 rows of letter material was measured. The reported row was always a word. In Exp I, the nonreported row contained either a word semantically related to the reported word, a nonassociated word, or a nonword. Nonwords were not used in Exp II. Attentional selectivity was varied by presenting a report cue either 250 msec prior to display onset or 250 msec after display onset. RT was faster when the report cue preceded the display, indicating that this cue induced selective attention. In both the selective and nonselective conditions, RT to name the target word was faster when the nonreported row contained a word associated with the target than when it contained a nonassociated word. However, this facilitation of RT produced by associated nonreported words was greater under the nonselective condition. While semantic information was extracted from both nonattended and attended visual material a larger semantic interaction occurred when attention was directed to both rows of a visual display. Results also indicate that the presence of nonwords influenced the strategy used to analyze a visual display. (French summary) (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marginal and extramarginal cortical lesions and visual discrimination by cats.

75 mongrel cats learned a shape discrimination with 0, 1, or 2 irrelevant cues. They were then subjected to either sham operations, ablation of the marginal and splenial gyri, or lesions in the extramarginal (EM) cortex. The 32 EM cats comprised 4 groups, 3 with small (EM1), intermediate (EM2), large (EM3) decortications, and a 4th group with both EM lesions and heavy degeneration in the lateral geniculate nucleus (LGN). Ss with marginal or extensive extramarginal lesions were severely impaired in shape and size discrimination. Results show the following: (a) The errors made by marginal gyrus cases increased sharply as a function of the number of irrelevant cues present in shape discrimination training; no other group, including Group EM3, was affected by this variable. (b) Ss with extramarginal ablations and strong LGN degeneration were no more severely impaired than were Ss with comparable extramarginal damage and little or no LGN degeneration. While the nature of the 2 kinds of deficits remains unclear, they seem parallel to those following posterior cortical lesions in monkeys. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orthographic and lexical processing of visual letter strings.

Three experiments tested whether orthographic and lexical properties of a letter string influence the time to search for a component letter. 102 Canadian undergraduates served as Ss. Orthographic redundancy, defined by single-letter position-specific frequency, facilitated the search of targets specified prior to and simultaneously with the letter string. Words were searched faster than nonwords when the target followed the letter string. Neither orthographic nor lexicality had significant effects when the position of the target within the string was certain. Results are consistent with a hierarchical-levels model of word perception in which the activation of detectors at different levels is constrained by task demands. (French abstract) (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)