Short‐term trained lexical categories produce preattentive categorical perception of color: Evidence from ERPs

The present study investigated whether short‐term trained lexical categories could produce lateralized preattentive categorical perception (CP) of color. Participants' event‐related potentials were recorded while performing a visual oddball task in which standard and deviant colored stimuli from the same or different novel lexical categories were presented. Two groups of participants were recruited: a group trained on these novel categories (n = 26), and an untrained control group (n = 26). Results of paired t tests showed that deviants did not evoke significant visual mismatch negativity, with the exception of deviants from different novel categories presented in the right visual field of the training group. This suggests that short‐term trained lexical categories produce lateralized preattentive color CP, and language enhances sensitivity to the differences among between‐category stimuli.     

Short‐term trained lexical categories affect preattentive shape perception: Evidence from vMMN

Perceptual processing of colors and shapes in the right visual field is modulated by the lexical category information of the stimuli, a phenomenon known as the lateralized Whorfian effect. For color stimuli, lateralized Whorfian effect is characterized by preattentive occurrence and dependency on acquired lexical information, but it remains unknown whether these key features are generalizable to other domains of perceptual processing. Here, we investigated whether lateralized Whorfian effect in the shape perception domain also depends on acquired lexical category and occurs preattentively using ERPs. Participants were trained to associate novel, irregular polygons with lexical category labels via short‐term intensive training. Using the visual oddball paradigm, we found stronger visual mismatch negativity (vMMN) component elicited by the deviant stimuli whose lexical category differed from the standard stimuli when the deviant was presented in the right visual field, indicating higher perceptual conspicuity for between‐category stimuli. These findings provide direct evidence of similar preattentive lexical category‐contingent modulation on shape perception akin to color perception, suggesting that the lateralized Whorfian effect is not epiphenomenal but rather might reflect the interaction between higher‐level lexical processing and the lower‐level perceptual processing more broadly.     

Brain activity from stimuli that are not perceived: Visual mismatch negativity during binocular rivalry suppression

Predictive coding explains visual perception as the result of an interaction between bottom‐up sensory input and top‐down generative models at each level of the visual hierarchy. Evidence for this comes from the visual mismatch negativity (vMMN): a more negative ERP for rare, unpredictable visual stimuli—deviants, than for frequent, predictable visual stimuli—standards. Here, we show that the vMMN does not require conscious experience. We measured the vMMN from monocular luminance‐decrement deviants that were either perceived or not during binocular rivalry dominance or suppression, respectively. We found that both sorts of deviants elicited the vMMN at about 250 ms after stimulus onset, with perceived deviants eliciting a bigger vMMN than not‐perceived deviants. These results show that vMMN occurs in the absence of consciousness, and that consciousness enhances the processing underlying vMMN. We conclude that generative models of visual perception are tested, even when sensory input for those models is not perceived.     

The quest for the genuine visual mismatch negativity (vMMN): Event-related potential indications of deviance detection for low-level visual features

Research shows that the visual system monitors the environment for changes. For example, a left-tilted bar, a deviant, that appears after several presentations of a right-tilted bar, standards, elicits a classic visual mismatch negativity (vMMN): greater negativity for deviants than standards in event-related potentials (ERPs) between 100 and 300 ms after onset of the deviant. The classic vMMN is contributed to by adaptation; it can be distinguished from the genuine vMMN that, through use of control conditions, compares standards and deviants that are equally adapted and physically identical. To determine whether the vMMN follows similar principles to the auditory mismatch negativity (MMN), in two experiments we searched for a genuine vMMN from simple, physiologically plausible stimuli that change in fundamental dimensions: orientation, contrast, phase, and spatial frequency. We carefully controlled for attention and eye movements. We found no evidence for the genuine vMMN, despite adequate statistical power. We conclude that either the genuine vMMN is a rather unstable phenomenon that depends on still-to-be-identified experimental parameters, or it is confined to visual stimuli for which monitoring across time is more natural than monitoring over space, such as for high-level features. We also observed an early deviant-related positivity that we propose might reflect earlier predictive processing.