Masked repetition priming and event‐related brain potentials: A new approach for tracking the time‐course of object perception

Abstract

This study reports a new approach to studying the time-course of the perceptual processing of objects by combining for the first time the masked repetition priming technique with the recording of eventrelated potentials (ERPs). In a semantic categorization task ERPs were recorded to repeated and unrelated target pictures of common objects that were immediately preceded by briefly presented pattern masked prime objects. Three sequential ERP effects were found between 100 and 650 ms post-target onset. These effects included an early posterior positivity/anterior negativity (N/P190) that was suggested to reflect early feature processing in visual cortex. This early effect was followed by an anterior negativity (N300) that was suggested to reflect processing of object-specific representations and finally by a widely distributed negativity (N400) that was argued to reflect more domain general semantic processing.

Pictorial Cognitive Task Resolution and Dynamics of Event-Related Potentials

“…Thus the N300 probably refl ects early semantic categorization of an object, which occurs prior to the determination of more specifi c identity information. Eddy et al 17 also state that the anterior negativity (N300) refl ects processing of object-specifi c representations.…”

An ERP investigation of location invariance in masked repetition priming

“…This component took the form of a larger negativity to target words that were unrelated to their preceding prime words (e.g., phone-truck), intermediate for targets that overlapped with primes in all but one letter position (e.g., trock-k k truck), and smallest for complete repetitions (e.g., truck-k k truck). Grainger and Holcomb (in press) have argued that such N250 effects, which were not seen for individual letters (Petit et al, 2006) or objects (Eddy et al, 2006), reflect the process whereby prelexical orthographic representations (letters and letter clusters) are mapped onto whole-word orthographic representations.…”

View-sensitive ERP repetition effects indicate automatic holistic processing of spatially unattended objects

“…These repetition effects post-400 ms are qualitatively different to the N1 and N250, and have been associated with conceptual processing for example by Henson et al (2004) who observed repetition effects between (400-500 ms) elicited by attended objects, and Eddy et al (2006) who observed repetition effects between (350-650 ms) elicited by masked primes.…”

“…However, there is some debate as to what degree visual masking renders a stimulus 'unattended' (Henson, 2003) rather than just harder to see. In addition, the study of Eddy et al (2006) presented prime and probe stimulus (even if temporally separated) in the same location and this type of manipulation may not fully prevent the prime from being attended as the task does not involve the necessity for an attentional shift (cf. Wolfe, 2000; Experiment 1 of Lachter et al, 2004).…”

“…One example of an ERP study on unattended objects is that of Eddy et al (2006), who used visual masking to render objects invisible to be processed without attention. They observed more negative amplitude deflections at occipital (O1/2) scalp locations for repeated objects within the time windows of N/P190 (100-250 ms), N300 (250-350 ms) and N400 (350-650 ms), indicating visual processing of unattended objects.…”