Quantum mechanics

Cognitive psychology

Communication

Neuroscience

Biology

Identification (biology)

N400

Cognition

Nuclear magnetic resonance

Semantic similarity

Operating system

Categorical perception

Computer science

Botany

Speech perception

Natural language processing

Physics

Psychology

Semantic memory

Object (grammar)

Artificial intelligence

Medicine

Categorical variable

Perception

Electromagnetic coil

Audiology

Peripheral

Event-related potential

Machine learning

Electroencephalography and Clinical Neurophysiology

Objectives: The aim of this study was to examine the N300 and N400 effect to pictures that were semantically incongruous to a prior object name. Based upon theories of object identification, the semantic incongruity was manipulated to occur early or late in the object processing stream.Methods: High-density visual event-related potentials were measured in response to passively viewed black and white line drawings of common objects. Pictures were preceded with an object name at either the basic (categorical) or subordinate (specific) level. The object either matched or mismatched with the name. With subordinate level names, mismatches could be within- or between-category.Results: The N400 effect was found for both basic and subordinate level mismatches. The N400 was found for both the subordinate-within and subordinate-between. Comparison of the scalp distributions between these N400 effects suggested a common effect was found for all conditions. The N300 effect, however, was only found for between-category mismatches, and only when semantic expectations were high in the match baseline (subordinate matches).Conclusions: The findings are consistent with theories of object identification that suggest that objects are initially categorized prior to being identified at more specific levels. The N300 appears to reflect the categorisation while the N400 effect appears to be responsive to all semantic mismatches. Comparison of scalp topographies, functional differences, and different estimated cortical source locations suggest that the N300 and N400 are two distinct semantic effects that reflect aspects of object identification.

Magnetic coil supression of peripheral visual perception using disappearance targets