There is an ongoing debate about whether involuntary shifts of attention, elicited by non-predictive peripheral cues, enhance perception. On the one hand, there is evidence that involuntary attention improves accuracy on tasks mediated by contrast sensitivity (e.g., Giordano, McElree, & Carrasco,
2009; Liu, Pestilli, & Carrasco,
2005; Montagna, Pestilli, & Carrasco,
2009; Pestilli & Carrasco,
2005; Pestilli, Viera, & Carrasco,
2007; Scolari, Kohnen, Barton, & Awh,
2007) and increases the apparent contrast of cued stimuli (Carrasco, Ling, & Read,
2004; Fuller, Park, & Carrasco,
2009; Fuller, Rodriguez, & Carrasco,
2008). On the other hand, there is evidence that non-predictive cues do not improve perception, whereas predictive cues do (Kerzel, Zarian, & Souto,
2009; Prinzmetal, McCool, & Park,
2005; Prinzmetal, Park, & Garrett,
2005), and that effects of peripheral cues on perceived contrast are due to decision bias (Kerzel, Zarian, Gauch, & Buetti,
in press; Prinzmetal, Long, & Leonardt,
2008; Schneider & Komlos,
2008; Valsecchi, Vescovi, & Turatto,
2010) (but see Carrasco, Fuller, & Ling,
2008). In view of the large literature on this topic, the debate about involuntary cueing effects on accuracy measures has to be qualified by at least two factors: the stage at which attentional effects occur (perceptual enhancement vs. decision making) and the type of perceptual enhancement (contrast enhancement, more efficient transfer into visual short-term memory, noise exclusion, etc.).