The present review focuses on the utility of the amplitude of P3 of as a measure of processing capacity and mental workload. The paper starts with a brief outline of the conceptual framework underlying the relationship between P3 amplitude and task demands, and the cognitive task manipulations that determine demands on capacity. P3 amplitude results are then discussed on the basis of an extensive review of the relevant literature. It is concluded that although it has often been assumed that P3 amplitude depends on the capacity for processing task relevant stimuli, the utility of P3 amplitude as a sensitive and diagnostic measure of processing capacity remains limited. The major factor that prompts this conclusion is that the two principal task variables that have been used to manipulate capacity allocation, namely task difficulty and task emphasis, have opposite effects on the amplitude of P3. I suggest that this is because, in many tasks, an increase in difficulty transforms the structure or actual content of the flow of information in the processing systems, thereby interfering with the very processes that underlie P3 generation. Finally, in an attempt to theoretically integrate the results of the reviewed studies, it is proposed that P3 amplitude reflects activation of elements in a event-categorization network that is controlled by the joint operation of attention and working memory.

On the utility of P3 amplitude as a measure of processing capacity

Event-related potentials, lexical decision and semantic priming

Event-related brain potentials (ERPs) were recorded as subjects silently read a set of unrelated sentences. The ERP responses elicited by open-class words were sorted according to word frequency and the ordinal position of the eliciting word within its sentence. We observed a strong inverse correlation between sentence position and the amplitude of the N400 component of the ERP. In addition, we found that less frequent words were associated with larger N400s than were more frequent words, but only if the eliciting words occurred early in their respective sentences. We take this interaction between sentence position and word frequency as evidence that frequency does not play a mandatory role in word recognition, but can be superseded by the contextual constraint provided by a sentence.

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Interactions between sentence context and word frequency in event-related brain potentials.

The stimulus evaluation view on P3 latency holds that P3 latency mainly reflects stimulus-processing time, in contrast to response-processing lime. A review of the experimental evidence, however, leads to the conclusion that P3 is not a sensitive tool for separating between stimulus and response-related processes. Rather, it appears that P3 latency is a sensitive index of any response-time changes when response times in the fast condition are brief, with its sensitivity decreasing when response times in the fast condition get longer. This regularity was confirmed by a detailed analysis of the published evidence from Steinberg's task and was not attributable to speed-accuracy trade-off or to different methods of parameterization. The structures generating the scalp P3b are involved both in stimulus processing and in response selection. Response selection may exert its effect on P3 in one of two ways: either directly, fully delaying P3 latency, or affecting a second P3 component (P-CR) only, thus having an attenuated effect on P3 latency.

On the utility of P3 latency as an index of mental chronometry.

Event-related potential (erp) reflections of mental resources: a review and synthesis

Event-related potentials during naming and mental rotation ☆

The ability to name an object is a basic language skill. Anomia, the inability to name an object, is a common language impairment occurring in the course of most aphasic disorders and as part of other more diffuse brain disturbances (Benson, 1979). Different types of aphasia are associated with different kinds of naming impairment (Goodglass and Baker, 1976; Grossman, 1978). Aphasic patients vary in their ability to benefit from cues (Barton, 1971), to retrieve a word from memory (Goodglass et al., 1976), or to respond to different modalities of presentation (Goodglass and Stuss, 1979). The naming task is therefore a valuable tool for understanding the functional organization of language in the brain. We evaluated the event-related potentials occurring in association with naming in a group of normal subjects. Our results could then serve as a basis for the use of event-related potentials in the investigation of language disorders.

F. F. Sarazin

Papers

Event-related potentials during naming and mental rotation ☆

Event-related potentials during naming.