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Biomedical subjects

N Lavie

Publications and source records attributed to N Lavie.

11 recordsLinked to original sources
PubMed1999

Effect of articulatory and mental tasks on postural control.

The present study sought to determine whether the increased postural instability produced by a spoken mental task was due to competing demands for attentional resources or perturbation of posture by articulation. Postural sway was measured in 36 normal subjects under the following conditions: repeating a number aloud (articulation), counting backwards aloud in multiples of seven (articulation and attention), counting backwards silently (attention), and no mental task (neither articulation nor attention). Articulation resulted in a significant increase in sway, whereas no effect of attention was observed. We conclude that in order to accurately assess the effect of attentional demands on postural control, it is important to eliminate or control the effects of articulation.

Adolescent↗
PubMed1998

The influence of perceptual load on age differences in selective attention.

The effect of perceptual load on age differences in visual selective attention was examined in 2 studies. In Experiment 1, younger and older adults made speeded choice responses indicating which of 2 target letters was present in a relevant set of letters in the center of the display while they attempted to ignore an irrelevant distractor in the periphery. The perceptual load of relevant processing was manipulated by varying the central set size. When the relevant set size was small, the adverse effect of an incompatible distractor was much greater for the older participants than for the younger ones. However, with larger relevant set sizes, this was no longer the case, with the distractor effect decreasing for older participants at lower levels of perceptual load than for younger ones. In Experiment 2, older adults were tested with the empty locations in the central set either unmarked (as in Experiment 1) or marked by small circles to form a group of 6 items irrespective of set size; the 2 conditions did not differ markedly, ruling out an explanation based entirely on perceptual grouping.

Adult↗
PubMed1997

Modulating irrelevant motion perception by varying attentional load in an unrelated task.

Lavie's theory of attention proposes that the processing load in a relevant task determines the extent to which irrelevant distractors are processed. This theory was tested by asking participants in a study to perform linguistic tasks of low or high load while ignoring irrelevant visual motion in the periphery of the display. Although task and distractor were unrelated, both functional imaging of motion-related activity in cortical area V5 and psychophysical measures of the motion aftereffect showed reduced motion processing during high load in the linguistic task. These findings fulfill the prediction that perception of irrelevant distractors depends on the relevant processing load.

Adult↗
PubMed1997

Contrast discrimination function: spatial cuing effects.

The effects of spatial cuing were measured for discrimination between an increment and a decrement on a target's pedestal contrast. Discrimination thresholds measured in the absence of a spatial cue were always higher than corresponding thresholds measured in the presence of a spatial cue, except when pedestal contrast was near zero. Uncued discrimination thresholds rose monotonically with pedestal contrast; cued discrimination thresholds formed a dipper function of pedestal contrast. A spatial-uncertainty model incorporating a nonlinear transducer produced similar results.

Contrast Sensitivity↗
PubMed1997

Visual feature integration and focused attention: response competition from multiple distractor features.

Predictions from Treisman's feature integration theory of attention were tested in a variant of the response-competition paradigm. Subjects made choice responses to particular color-shape conjunctions (e.g., a purple cross vs. a green circle) while withholding their responses to the opposite conjunctions (i.e., a purple circle vs. a green cross). The results showed that compatibility effects were based on both distractor color and shape. For unattended distractors in preknown irrelevant positions, compatibility effects were equivalent for conjunctive distractors (e.g., a purple cross and a blue triangle) and for disjunctive distractors (e.g., a purple triangle and a blue cross). Manipulation of attention to the distractors positions resulted in larger compatibility effects from conjoined features. These results accord with Treisman's claim that correct conjunction information is unavailable under conditions of inattention, and they provide new information on response-competition effects from multiple features.

Adult↗
PubMed1996

On the spatial extent of attention in object-based visual selection.

A new test was devised to avoid previous confounds in measures of object-based limits on divided visual attention. The distinction between objects was manipulated across a wide spatial extent. Target elements appeared on the same object only when far apart, and appeared close only when on different objects, so that object effects could not be reduced to spatial effects, nor vice versa. Subjects judged whether two odd elements within a display of two dashed lines were the same or different. They performed better when the target elements were far apart on a common line rather than on two distinct lines even though the latter arrangement was more likely. Thus, nonstrategic object-based limits on divided attention can arise even across large distances. However, when subjects were precued to expect targets in a narrow region of the display, the object effect was eliminated, implying that object-based selection may only operate within spatially attended regions.

Adolescent↗
PubMed1995

Perceptual load as a necessary condition for selective attention.

The early and late selection debate may be resolved if perceptual load of relevant information determines the selective processing of irrelevant information. This hypothesis was tested in 3 studies; all used a variation of the response competition paradigm to measure irrelevant processing when load in the relevant processing was varied. Perceptual load was manipulated by relevant display set size or by different processing requirements for identical displays. These included the requirement to process conjunctions versus isolated features and the requirement to perform simple detection of a character's presence versus difficult identification of its size and position. Distractors' interference was found only under low-load conditions. Because the distractor was usually clearly distinct from the target, it is concluded that physical separation is not a sufficient condition for selective perception; overloading perception is also required. This allows a compromise between early and late selection views and resolves apparent discrepancies in previous work.

Adult↗
PubMed1994

The role of attention in illusory conjunctions.

In five experiments, we investigated the effects of attention on illusory conjunctions formed between features of unrelated objects. The first three experiments used a weak manipulation of attention and found that illusory conjunctions formed either among features receiving high attentional priority or among features receiving low attentional priority were not more frequent than were conjunctions formed between mixed features of different attentional priority. The last two experiments used a strong manipulation of attention and failed to reveal any evidence of true illusory conjunctions. The results are inconsistent with the feature-integration theory, which predicts that when attention is focused on a subset of items, illusory conjunctions ought to occur within and outside of the attended subset, but not between the attended and unattended items.

Attention↗
PubMed1994

Perceptual load as a major determinant of the locus of selection in visual attention.

In this paper, we propose that the debate concerning the locus of attentional selection can be resolved by specifying the conditions under which early selection is possible. In the first part, we present a theoretical discussion that integrates aspects from structural and capacity approaches to attention and suggest that perceptual load is a major factor in determining the locus of selection. In the second part, we present a literature review that examines the conditions influencing the processing of irrelevant information. This review supports the conclusion that a clear physical distinction between relevant and irrelevant information is not sufficient to prevent irrelevant processing; early selection also requires that the perceptual load of the task be sufficiently high to exceed the upper limit of available attentional resources.

Attention↗
PubMed1993

Location dominance in attending to color and shape.

Four experiments investigated whether Ss direct attention to stimulus location when attempting to attend to its color or shape. In the first 2 experiments a given property (location, color, or shape) of a letter cue instructed Ss whether to report any letters from a subsequent display. Regardless of which property was relevant, Ss reported letters adjacent to the cue and not those similar to its color or shape. In the last 2 experiments, the varied location of a cue was irrelevant to the task, whereas its varied color instructed Ss to report a letter in a given location or of a given shape. Targets adjacent to the cue were reported faster than those remote from the cue. The results suggest that attempting to attend to any aspect of a stimulus entails directing attention to its location.

Adult↗