Spatial cueing deficits in dyslexia reflect generalised difficulties with attentional selection.
Traditionally, explanations of spatial cueing effects posit the operation of orienting mechanisms that act to reposition the spatial locus of attention. This process is often viewed to be analogous to the movement of an attentional 'spotlight' across the visual field to the cued region and is thought to occur either in an exogenous or endogenous manner, depending on the nature of the cue. In line with this view, anomalous findings in dyslexic groups using paradigms involving brief peripheral cues have been interpreted as evidence for a particular deficiency with stimulus-driven, exogenous orienting. Here, we demonstrate that an exogenous orienting deficit is an unfeasible explanation of recent findings in which dyslexic individuals fail to derive benefit from peripheral cues indicating the location of a target in a single fixation visual search task. In a series of experiments examining cueing effects in normal readers, we find no evidence to support the operation of an attentional orienting mechanism that is (i) fast but transient; (ii) automatic and involuntary; and (iii) preferentially driven by abrupt luminance transients. Rather, we find that the magnitude of obtained benefits is primarily determined by the informational value of the cue (irrespective of how information is conveyed) and the accessibility of the target representation once the cue had been delivered. In addition, we show that dyslexic individuals' difficulties with cued search do not reflect problems with detecting and localising the cue, and generalize to different cue types. These results are consistent with a general weakness of attentional selection in dyslexia.
Roach
Neil W
NW
Visual Neuroscience Group, School of Psychology, The University of Nottingham, University Park, Nottingham NG7 2RD, UK. nwr@psychology.nottingham.ac.uk
Hogben
John H
JH
D000328:Adult; D001288:Attention; D015350:Contrast Sensitivity; D003463:Cues; D004410:Dyslexia / Q000503:physiopathology / Q000523:psychology*; D005403:Fixation, Ocular; D006801:Humans; D009949:Orientation; D011601:Psychophysics; D013028:Space Perception