Abstract
Does knowing what one is about to see make it easier to see it? The answer may depend on the source of the knowledge. A great deal of evidence indicates that allocating visual attention to a stimulus or location improves reaction times (Posner, Snyder, & Davidson, 1980), detection sensitivity (Hawkins et al., 1990) and perceived contrast (Carrasco, Ling, & Read, 2004). Higher-level knowledge also seems to influence visual perception. For instance, processing verbs representing directions of motions increases sensitivity to congruent motion in random-dot kinematograms (Meteyard, Bahrami, Vigliocco, in press). Here, we show that hearing, but not seeing object names facilitates visual object detection in what may be a top-down effect of verbally presented object-names on visual processing.
Participants completed an object detection task in which they made an object-presence or -absence decision to uppercase letters presented briefly (50 ms) at or near fixation. Participants heard (Auditory condition) or saw (Visual condition) cues on 50% of the trials informing them of what letter to expect on the upcoming trial. The auditory cues consisted of recorded letter names (e.g., “emm”) and the visual cues consisted of letters of the same size and in the same position as the to-be-detected stimulus. Both cue types were presented for 650 ms. When present, the stimulus appeared 1600 ms after cue offset and was masked by a random mask for 750 ms.
Only the auditory cues increased sensitivity (d') compared to baseline no-cue trials. Additional experiments showed that facilitated object detection following auditory cues: a) persisted when the exact position of the to-be-detected stimulus was unknown, b) could not be attributed to general arousal due to auditory input, and c) the increase in sensitivity was specific to the cued letter. Moreover, participants who reported more vivid visual imagery (VVIQ: Marks, 1973) showed greater facilitation following auditory cues.