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A F Kramer

Publications and source records attributed to A F Kramer.

70 records · Page 4Linked to original sources
PubMed1991

Perceptual organization and focused attention: the role of objects and proximity in visual processing.

The influence of the Gestalt grouping principles of similarity, closure, and proximity on the size of the response-compatibility effect was examined in a focused attention task. In three studies, subjects responded to a centrally located target and attempted to ignore adjacent distractors. The distractors, which served as targets on other trials, could be compatible, incompatible, or neutral with respect to the response of the target. In addition, the distractors and the target could be embedded in the same object, presented in the same color, presented on different objects, or presented in different colors. The typical response-compatibility effect (B. A. Eriksen & C. W. Eriksen, 1974) was found when the target and distractors were embedded in the same object or presented in the same color. Performance was poorer when the target was surrounded by response-incompatible distractors than when it was surrounded by response-compatible distractors. However, the response-compatibility effect was eliminated when the target and distractors were embedded in different objects, even when the distance between the items was less than .25 degrees of visual angle. Furthermore, the response-compatibility effect was of intermediate size when the distractors were not grouped strongly with the target or with neutral flankers. The results are discussed in terms of space- and object-based models of visual attention.

Adolescent↗
PubMed1991

Movement and focused attention: a failure to replicate.

Our original goal was to explore the nature of the grouping-by-movement phenomenon reported by Driver and Baylis (1989). In their studies, distractors that moved in common with a centrally located target had a larger influence on focused-attention performance than did more proximate but stationary distractors. These results seemed particularly important since they suggested, contrary to the predictions of space-based models of attention, that attention could be allocated to noncontiguous regions of the visual field. Their results also suggested mandatory processing of stimuli with common motion. Unfortunately, we were unable to replicate this grouping-by-movement effect. In the conditions of Experiment 1 in which we replicated Driver and Baylis's methodology, stationary distractors produced a larger response-compatibility effect than did the more distant distractors that moved in common with the target. In Experiment 2, we redundantly coded the centrally located target and the far distractors with common movement and color. However, the results were identical to those obtained in Experiment 1. The stationary near distractors that appeared in a different color from the target and the far distractors produced the largest response-compatibility effect. In a final experiment, we attempted to compensate for the reduced acuity of the moving distractors by adjusting their size by a cortical magnification factor. However, even with this manipulation, we found a larger response-compatibility effect for the stationary near distractors than for the moving distant distractors. Our results suggest that subjects are capable of selectively processing a target item that moves in common with distractors.

Adolescent↗
PubMed1990

Event-related brain potentials as indices of information extraction and response priming.

Measures of overt response and of the event-related brain potential (ERP) were used to investigate the processing of a priming stimulus varying in its information content. Subjects were shown sequences of 2 letters that served as a priming and an imperative stimulus. In 3 randomly interspersed conditions the imperative stimulus had a 0.80, 0.50, or 0.20 probability of physically matching the priming letter. The different probability conditions were signaled by the position of a dot flanking the priming letter. Reaction time and accuracy data indicated that the subjects primed their responses as a function of the information conveyed by the priming stimulus. The amplitude and latency of the P300 to the priming stimulus were sensitive to the amount of information conveyed by the priming stimulus and the duration of the processing required. The readiness potential in the foreperiod was lateralized as a function of the priming stimulus. Furthermore, the larger the amplitude of the P300 to the priming stimulus, the larger the lateralization of the readiness potential, indicating that information extraction, indexed by the P300, was related to response priming, indexed by the readiness potential. The results indicate that ERP measures make manifest covert aspects of the priming process occurring in the foreperiod.

Adolescent↗
PubMed1990

Development and transfer of automatic processing.

Two studies were performed to examine the role of consistency in the development and transfer of automatic processing. Ss performed a rule-based memory search task in which they compared multidimensional probes to 1, 2, or 3 memory set rules. Results indicated that learning occurred in the absence of consistency at lower levels of task description (e.g., mapping of individual task components to responses) as long as higher level consistencies existed in the task (e.g., consistent) mapping of task components to a conceptual framework). However, the asymptotic level of this learning was modulated by the consistency with which conjunctions of task components were mapped to decisions. High positive transfer was obtained despite replacement of the exemplars of the memory set rules, suggesting that learning was not specific to the items encountered during training. On the other hand, the magnitude of positive transfer was reduced when the rules were replaced, suggesting that most of the learning took place at the level of specific rules. Some evidence was also obtained for more general process-based learning. Results are discussed in terms of their implications for models of learning and transfer.

Adolescent↗
PubMed1990

An analysis of memory-based theories of automaticity.

Memory-based theories of automaticity predict that performance in a memory search task which is automatic will not require a representation of the memory set in working memory. The information contained in working memory was manipulated by inserting an interference task between the presentation of a memory set and a probe stimulus in a memory search task. The interference task prevented rehearsal, necessitating the retrieval of the memory set from long-term memory in variably mapped (VM) conditions. Performance in consistently mapped (CM) conditions provided strong support for memory-based theories of automaticity. With CM practice, both the effects of memory load and the effect of the interference task were eliminated. Furthermore, there was a temporal coupling in the reduction of these two effects with consistent practice. Monte Carlo simulations of memory-based automaticity predict such a temporal coupling. Automaticity is viewed as a continuum reflecting the relative contribution of the direct memory access of past solutions from long-term memory on performance.

Adolescent↗
PubMed1989

Resource reciprocity: an event-related brain potentials analysis.

The amplitude of the P300 component of the Event-Related Potential (ERP) has proven useful in identifying the resource requirements of complex perceptual-motor tasks. In dual-task conditions, increases in primary task difficulty result in decreases in the amplitude of P300s elicited by secondary tasks. Furthermore, P300s elicited by discrete primary task events increase in amplitude with increases in the difficulty of the primary task. The reciprocity in P300 amplitudes has been used to infer the processing tradeoffs that occur during dual-task performance. The present study was designed to investigate further the P300 amplitude reciprocity effect under conditions in which primary and secondary task ERPs could be concurrently recorded within the same experimental situation. Forty subjects participated in the study. Measures of P300 amplitude and performance were obtained within the context of a pursuit step tracking task (the primary task) performed alone and with a concurrent auditory discrimination task (the secondary task). Primary task difficulty was manipulated by varying both the number of dimensions to be tracked (from one to two), and the control dynamics of the system (velocity or acceleration). ERPs were obtained from both secondary task tones and primary task step changes. Average root-mean-square (RMS) error estimates were also obtained for each tracking condition. Increased primary task difficulty, reflected in increased RMS error scores, was associated with decreased secondary task P300 amplitudes and increased primary task P300 amplitudes. The increases in primary task P300 amplitudes were complementary to the decrements obtained for the secondary task, supporting the hypothesis of reciprocity between primary and secondary task P300 amplitudes across different manipulations of primary task difficulty.

Adolescent↗
PubMed1989

Simulation studies of latency measures of components of the event-related brain potential.

We compared the accuracy of P300 latency estimates obtained with different procedures under several simulated signal and noise conditions. Both preparatory and signal detection techniques were used. Preparatory techniques included frequency filters and spatial filters (single electrode selection and Vector filter). Signal detection techniques included peak-picking, cross-correlation, and Woody filter. Accuracy in the latency estimation increased exponentially as a function of the signal-to-noise ratio. Both Woody filter and cross-correlation provided better estimates than peak-picking, although this advantage was reduced by frequency filtering. For all signal detection techniques, Vector filter provided better estimates than single electrode selection. Large component overlap impaired the accuracy of the estimates obtained with both single electrode selection and Vector filter, but with Vector filter impairment occurred only when the overlapping component had a scalp distribution that was similar to the scalp distribution of the signal component. The effects of varying noise characteristics, P300 duration and latency, and the parameters of Vector filter were also investigated.

Arousal↗
PubMed1988

Assessing the development of automatic processing: an application of dual-task and event-related brain potential methodologies.

Previous research has found that properties of automatic processing do not always co-occur, suggesting that the acquisition rates may differ. The present study investigated the acquisition rate of several of these properties by employing additive factors logic, dual task methodology, and event-related brain potentials. Seven subjects participated in a ten session experiment in which they performed two tasks, a visual/memory search task and a pursuit step tracking task, both together and separately. RT and P300 latency measures indicated that parallel processing of the display was achieved early in training in the consistent mapping condition. This processing was unaffected by dual task demands. An analysis of RT/P300 ratios suggests that another form of perceptual efficiency was achieved later in practice in both the varied and consistently mapped search tasks. This effect was larger in the consistent mapping condition. Reductions in the slope of the memory set function occurred significantly earlier for P300 latency than for RT, suggesting that the stimulus evaluation processes became automated more rapidly than the response selection components of memory search. Consistent with an analysis of the processing demands of the two tasks, the introduction of the tracking task and an increase in tracking difficulty produced equivalent interference during consistent and varied mapping conditions. Results are discussed in terms of models of skill, skill acquisition and component task automaticity.

Adult↗
PubMed1987

Brain potentials as indices of orthographic and phonological interaction during word matching.

The interaction between orthographic and phonological codes in a same-different judgment task was studied by requiring subjects to decide if two visually presented words either looked alike or rhymed. Word pairs were selected from four different lists. Words rhymed and looked alike, rhymed but did not look alike, looked alike but did not rhyme, or neither looked alike nor rhymed. Reaction time and percent error increased whenever there was a conflict between the orthography and phonology of the words. The N200 component of the event-related brain potential (ERP) indicated that subjects were capable of detecting phonological differences between words within 260 ms from the presentation of a word pair. The amplitude of the N200s also varied with the degree of mismatch between words. N200s were largest when both the orthography and phonology mismatched, of intermediate amplitude when either orthography or phonology mismatched, and smallest when both orthography and phonology matched. P300 latency was consistent with reaction time, increasing whenever there was a conflict between the two codes. Taken together, behavioral measures and the ERP data suggest that the extraction of the orthographic and phonological aspects of words occurs early in the information processing sequence.

Evoked Potentials, Visual↗
PubMed1985

Processing of stimulus properties: evidence for dual-task integrality.

The conditions under which dual-task integrality can be fostered were assessed in a study in which we manipulated four factors likely to influence the integrality between tasks: intertask redundancy, the spatial proximity of primary and secondary task displays, the degree to which primary and secondary task displays constitute a single object, and the resource demands of the two tasks. The resource allocation policy is inferred from changes in the amplitude of the P300 component of the event-related brain potential. Twelve subjects participated in three experimental sessions in which they performed both single and dual tasks. The primary task was a pursuit step tracking task. The secondary tasks required subjects to discriminate between different intensities or different spatial positions of a stimulus. Task pairs that required the processing of different properties of the same object resulted in better performance than task pairs that required the processing of different objects. Furthermore, these same object task pairs led to a positive relation between primary task difficulty and the resources allocated to secondary task stimuli. Intertask redundancy and the physical proximity of task displays produced similar effects of reduced magnitude.

Adolescent↗
PubMedDate not supplied

Age-related differences in perceptual organization and selective attention: implications for display segmentation and recall performance.

The present research examined age-related differences in the use of structural aspects of the visual environment to facilitate the processing of task-relevant stimuli. More specifically, our study considered age-related differences in the use of color and proximity to facilitate the recall of alphabetic strings. The dependent measure of interest was the difference in percent recalled for items when grouped into the first or second of two groups that comprised the alphabetic string. When differences in visual short-term memory were controlled, old adults demonstrated a greater sensitivity to grouping by proximity and grouping by similarity than did younger adults. This increase in recall as a function of grouping is consistent with Craik's (1986) (In F. Klix & H. Hagendorf [Eds.], Human memory and cognitive capabilities, mechanisms, and performances [pp. 409-422]. North Holland: Elsevier) view that older adults can benefit when environmental support is provided for perception and memory components of task performance. The results suggest that applications employing multielement codes or signage may benefit from grouping together related or the most critical items. Most notably, this benefit would be as large or larger for the old than for the younger user populations.

Adolescent↗