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Attention allocation during sequential eye movement tasks

Martin Herbert Fischer, University of Massachusetts Amherst


This dissertation investigated the allocation of visuo-spatial attention during dynamic viewing. The hypothesis of an attentional focus that is initially centered at fixation and then shifts to the location of a forthcoming eye fixation prior to the overt eye movement was tested. Participants performed three different dual tasks while their eye movements and manual responses were recorded. The primary tasks all required sequential left-to-right eye movements; they were silent reading (Experiment 1), oculomotor scanning of text without vowels (Experiment 2), and visual search for a target letter (Experiment 3). A speeded manual response was made to an asterisk that appeared early or late after the onset of a critical fixation (25 or 170 ms probe delay), and either to the left of, or directly above, or to the right of the currently fixated character ($-$10, $-$5, 0, +5, or +10 characters probe eccentricity). It was predicted that early probes should be detected equally fast in the left and right hemifield, while responses to late probes should be faster when they appeared in the right than in the left visual hemifield. Selective facilitation of manual probe detection latencies near the location of the forthcoming eye fixation was found in the visual search task, but not during reading or scanning. Fixation times increased and saccade lengths decreased as a consequence of probing in all three tasks. Fixation durations were less prolonged when the probe appeared in the right than in the left hemifield; the critical saccades were largest when the probe appeared at +10 characters and smallest when it appeared at +5 characters eccentricity. In summary, detection latencies in the search task supported the attentional predictions, and the eye movement data provided consistent indirect support for the notion of attention shifts prior to eye movements. Task-specific processing demands may have diluted further evidence in the probe detection times from reading and scanning. Individual reaction times further revealed considerable intra- and interindividual differences. It is concluded that the present dual task combination with its dual motor response requirements may not be adequate to assess visuo-spatial attention allocation during sequential eye movement tasks.

Subject Area

Behaviorial sciences|Literacy|Reading instruction|Psychology|Experiments|Neurology

Recommended Citation

Fischer, Martin Herbert, "Attention allocation during sequential eye movement tasks" (1997). Doctoral Dissertations Available from Proquest. AAI9721447.