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Scott Watamaniuk, Satomi Maeda, Allen Nagy; Dividing attention between two simultaneous visual tasks: The Magnocellular system. Journal of Vision 2009;9(8):211. doi: 10.1167/9.8.211.
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© ARVO (1962-2015); The Authors (2016-present)
Attending to two simultaneous visual tasks results in varying degrees of interference. One model posits that the detection of parvocellular and magnocellular stimuli may require different amounts of attentional resources (Bonnel et al., 1992). Previous research (Maeda & Nagy, 2008) showed that simultaneously searching for two transient targets, coded by the magnocellular pathway, resulted in very little dual-task interference. However, though attention modulates motion cells in V1 (Watanabe et al, 1998) and MT/MST (Treue & Maunsell, 1999), mechanisms tuned to temporal frequency are partially separable from those tuned to velocity (e.g. Smith & Edgar, 1999). Thus we investigated the effect of dividing attention using both motion and transient stimuli to examine whether both types of magnocellular tasks would result in very little dual-task interference. In one experiment, observers simultaneously searched for a luminance transient target in each of two spatially separated, briefly presented arrays of stimuli. Luminance transients that resulted in 75% correct performance for each array in single-task conditions were then used in the dual-task conditions. In a second experiment, observers judged the direction of two simultaneously presented trajectories, one to the left and one to the right side of fixation, embedded in the random motion noise. Target trajectories appeared in one of 8 directions at 45-degree intervals. The number of noise dots that yielded approximately 75 % correct identification accuracy in single-task conditions was used in the dual-task conditions. Preliminary data show that two motion identification tasks result in more dual-task interference than two transient search tasks. The results will be discussed further in terms of a multiple resource model (Navon & Gopher, 1979), a shared resource sampling model (Miller & Bonnel, 1992), and a switching competition model (Duncan, 1980) of divided attention.
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