Orientation and contrast deviance examined: Contrast effects mimic deviant-related negativity yet neither produce the canonical neural correlate of prediction error.

The visual mismatch negativity (vMMN) is a negative-going event-related potential (ERP) component that is largest somewhere between 100 and 300 ms after the onset of an unpredictable visual event (i.e., a deviant) in an otherwise predictable sequence of visual events (i.e., standards). Many have argued that the vMMN allows us to monitor our ever-changing visual environment for deviants critical to our survival. Recently, however, it has become unclear whether unpredicted changes in low-level features of visual input, like orientation, can evoke the vMMN. I address this by testing isolated orientation changes, to confirm recent findings, and isolated contrast changes, to determine whether other low-level features of visual input do not evoke the vMMN in a traditional oddball paradigm. Eighteen participants saw sequences of rare, unanticipated, and different deviant stimuli, interspersed among frequent, anticipated, and identical standard stimuli. Stimuli were Gabor patches. Neither deviant produced a vMMN. Therefore, changes in low-level visual properties of well-controlled stimuli-a stimulus in which one property can be manipulated while all others remain unaffected-like Gabor patches do not yield a vMMN.