Unconscious processing of color and form in metacontrast masking

Abstract

Three experiments employed a metacontrast masking procedure to examine the extent and nature of priming effects from visual stimuli not consciously perceived. The results showed effects of unconscious stimuli on subsequent target responses that (1) were more consistent, reliable, and not subject to strategic control, as compared with consciously perceived stimuli (Experiment 1); (2) produced both facilitation and interference of subsequent processing (Experiment 2); and (3) did not influence indirect response-related levels of processing (Experiment 3). These results demonstrate that color and form attributes of unconscious stimuli are sufficiently registered within the visual system to influence behavior, and that some of these unconscious effects occur at early levels of stimulus encoding, prior to higher level perceptual and response-related processes.

Reversed Priming Effects May Be Driven by Misperception Rather than Subliminal Processing

“…In Van den Bussche et al (2013) study, participants reported their awareness of a prime word (“I am certain that I saw the color word Red,” “I think I saw the color word Red, but I am not certain,” and “I did not see the color word”) and the authors found the self-reports to be strongly associated with the size of the priming effects. This finding is in line with the results of other studies using a similar trial-based approach based on self-reports (e.g., Lamy et al, 2009; Ro et al, 2009). Van den Bussche et al (2013) also reported a statistically significant priming effect in the trials participants themselves reported to be unconscious (“I did not see the color word”; mean effect = 33 ms, 95% CI = 0.35–65.65 ms), indicating that Stroop priming can occur independent of perception (Van den Bussche et al, 2013).…”

“…Although dual-tasking may have some impact on priming effects, previous studies using dual-tasking have found strong priming effects (e.g., Kahan, 2000; Lamy et al, 2009; Ro et al, 2009; Finkbeiner, 2011; Goodhew et al, 2011; Van den Bussche et al, 2013). Dual-tasking can be difficult for the participant, however, so the experiment started with two training phases.…”

“…By comparing trials in which participants reported perceiving or not perceiving the prime, Van den Bussche et al (2013) were able to investigate whether a cognitive process was dependent on perception without proving that the stimulus was subliminal on a mean (group) level and while keeping signal intensity constant in both perceived and not-perceived trials. Similar trial-based analysis has been used to investigate perception-dependent processing in the past (e.g., Kahan, 2000; Lamy et al, 2009; Ro et al, 2009; Goodhew et al, 2011; Haase and Fisk, 2011; Peremen and Lamy, 2014; Hesselmann et al, 2015). …”

Higher-order awareness, misrepresentation and function

“…Or one could urge, with Block [14,18,19], that even some perceptual states that one is wholly unaware of and sincerely denies the occurrence of are conscious in a special way that does not require any such awareness. But states that occur in subliminal perception function in many or even most of the ways that conscious perceptual states function [59]. So denying that subliminal states are qualitative or even mental at all is simply redescribing commonsense phenomena to save a theoretical preconception.…”

Perceptual overloading reveals illusory contour perception without awareness of the inducers

“…In addition to illuminating the role of unconscious processing in human behavior, such knowledge might help us to better understand the role of consciousness in cognition. Although it is now widely accepted that low-level processing, such as the processing of color and shape (Breitmeyer, Ro, & Singhal, 2004;Klotz & Neumann, 1999;Ro et al, 2009;Schmidt, 2002), occurs unconsciously, evidence for unconscious high-level information processing remains mixed. For example, whereas some studies have shown cognitive control (e.g., conflict adaptation, error detection) without perceptual awareness (O'Connell et al, 2007;van Gaal, Lamme, & Ridderinkhof, 2010), other studies suggest that awareness is necessary for these high-level processes (Ansorge, Fuchs, Khalid, & Kunde, 2011;Kunde, 2003;Woodman, 2010).…”