Cue contrast modulates the effects of exogenous attention on appearance

Abstract

Exogenous spatial attention can be automatically engaged by a cue presented in the visual periphery. To investigate the effects of exogenous attention, previous studies have generally used highly salient cues that reliably trigger attention. However, the cueing threshold of exogenous attention has been unexamined. We investigated whether the attentional effect varies with cue salience. We examined the magnitude of the attentional effect on apparent contrast [Carrasco, M., Ling, S., & Read, S. (2004). Attention alters appearance. Nature Neuroscience, 7(3), 308–313.] elicited by cues with negative Weber contrast between 6% and 100%. Cue contrast modulated the attentional effect, even at cue contrasts above the level at which observers can perfectly localize the cue; hence, the result is not due to an increase in cue visibility. No attentional effect is observed when the 100% contrast cue is presented after the stimuli, ruling out cue bias or sensory interaction between cues and stimuli as alternative explanations. A second experiment, using the same paradigm with high contrast motion stimuli gave similar results, providing further evidence against a sensory interaction explanation, as the stimuli and task were defined on a visual dimension independent from cue contrast. Although exogenous attention is triggered automatically and involuntarily, the attentional effect is gradual.

A mathematical model of saccadic reaction time as a function of the fixation point brightness gain

“…2. Different from Fuller et al (2009), who found that attentional allocation is modulated by cue contrast, the modulation effect reported in this paper occurs at the fixation point, which the subject is already attending.…”

“…Furthermore, Fuller et al (2009) found that attention is modulated by cue contrast, concluding that although allocation of attention is automatic and unconscious, the attentional process is gradual rather than all-or-none.…”

“…There is evidence that higher-contrast cues attract more attention than lower-contrast cues (Fuchs & Ansorge, 2012;Fuller et al, 2009;Kean & Lambert, 2003). Furthermore, Fuller et al (2009) found that attention is modulated by cue contrast, concluding that although allocation of attention is automatic and unconscious, the attentional process is gradual rather than all-or-none.…”

Occipital TMS at phosphene detection threshold captures attention automatically

“…We found stronger capture for seen than for unseen cues, despite the two types of cue being physically identical. Attentional capture has recently been demonstrated to operate not as an all-ornone process but rather more gradually, with capture strength increasing with cue contrast (Fuller et al, 2009;Zehetleitner et al, 2013). Another body of work suggests that attentional capture can be modulated through top-down factors such as task set (Ansorge et al, 2011;Folk et al, 1992;Hsieh et al, 2011).…”

“…Some studies reported capture by lowcontrast stimuli, even below the threshold for conscious report (McCormick, 1997;Mulckhuyse et al, 2007). Furthermore, brighter stimuli capture attention more strongly than fainter stimuli (Fuller et al, 2009), indicating that capture is not a rigid, all-or-nothing phenomenon, but rather shows gradual scaling properties. Previous studies investigating the relationship between stimulus intensity and capture strength typically used either low or high intensities, rendering any direct comparisons difficult.…”