PubMed Health⌕ Search

Biomedical subjects

J Kounios

Publications and source records attributed to J Kounios.

14 recordsLinked to original sources
PubMed2001

Cognitive association formation in human memory revealed by spatiotemporal brain imaging.

Cognitive theory posits association by juxtaposition or by fusion. We employed the measurement of event-related brain potentials (ERPs) to a concept fusion task in order to explore memory encoding of these two types of associations between word pairs, followed by a memory test for original pair order. Encoding processes were isolated by subtracting fusion task ERPs corresponding to pairs later retrieved quickly from ERPs corresponding to pairs later retrieved slowly, separately for pairs fused successfully and unsuccessfully (i.e., juxtaposed). Analyses revealed that the encoding of these two types of associations yields different ERP voltage polarities, scalp topographies, and brain sources extending over the entire time course of processing.

Adult↗
PubMed2000

On the locus of the semantic satiation effect: evidence from event-related brain potentials.

The present study sought to determine whether semantic satiation is merely a by-product of adaptation or satiation of upstream, nonsemantic perceptual processes or whether the effect can have a locus in semantic memory. This was done by measuring event-related brain potentials (ERPs) in a semantic word-detection task involving multiple presentations of primes and critical related and unrelated words in three experiments involving visual (Experiment 1) and auditory (Experiments 2A and 2B) stimuli. Primes varied in their type case (Experiment 1) or pitch (Experiment 2B) in order to discourage sensory adaptation. Prime satiation and relatedness of the primes to the critical word had interacting effects on ERP amplitude to critical words, particularly within the time-window of the N400 component. Because numerous studies have indicated a role for the N400 in semantic processing, modulation of the N400 relatedness effect by prime satiation (with little or no contribution from perceptual adaptation) suggests that semantic memory can be directly satiated, rather than the cost to semantic processing necessarily resulting from impoverishment of perceptual inputs.

Adult↗
PubMed1999

Dual-coding, context-availability, and concreteness effects in sentence comprehension: an electrophysiological investigation.

Event-related potentials were recorded in 2 experiments while participants read sentences in a word-by-word congruency judgment task. Sentence final words were either congruent, semantically anomalous (Experiments 1 and 2), or neutral (Experiment 2) with respect to sentence context. Half of all final words referred to concrete and half to abstract concepts. A different scalp distribution of the N400 to concrete and abstract final words was found for anomalous and neutral, but not congruent sentences. Although the interaction of context and concreteness is consistent with the context-availability model, the differential scalp distribution of effects for concrete and abstract words, as well as larger context effects for concrete words, was interpreted as being more consistent with an extended dual-code account of semantic processing.

Adolescent↗
PubMed1997

Electrophysiological brain activity and memory source monitoring.

To investigate brain mechanisms involved in identifying the origin of memories, event-related potentials (ERPs) were recorded as participants discriminated previously presented (old) from new items or identified their earlier source (picture, word, or new). Differences in ERPs between old-new recognition and source identification were focused at frontal sites. For source identification, prominent negative deflections at occipital or frontal sites occurred depending on encoding task. These results support a model in which memory attributes are distributed neocortically and the frontal lobes are critical for source monitoring.

Discrimination Learning↗
PubMed1996

Electrophysiological brain activity and memory source monitoring.

To investigate brain mechanisms involved in identifying the origin of memories, event-related potentials (ERPs) were recorded as participants discriminated previously presented (old) from new items or identified their earlier source (picture, word, or new). Differences in ERPs between old-new recognition and source identification, were focused at frontal sites. For source identification, prominent negative deflections at occipital or frontal sites occurred depending on encoding task. These results support a model in which memory attributes are distributed neocortically and the frontal lobes are critical for source monitoring.

Adult↗
PubMed1996

Sudden insight: all-or-none processing revealed by speed-accuracy decomposition.

Issues surrounding the discreteness or continuity of cognitive processes have played a major role in experimental psychology, although there has been relatively little work that directly addresses these topics. Nevertheless, there has been a shift away from discrete models and toward continuous ones. The research reported in this article demonstrates discrete processing of information in an anagram task selected because of its similarity to insight problems, which seem subjectively to produce discrete "illumination" during processing. The authors used speed-accuracy decomposition (SAD), a relatively new technique for investigating the time course of information processing. The results of 2 experiments indicate little or no partial information in the anagram tasks, in contrast to previous research with SAD, all of which has revealed partial information. General models of human information processing must therefore be able to account for both patterns.

Cognition↗
PubMed1995

Speed-accuracy decomposition yields a sudden insight into all-or-none information processing.

The existence of discrete all-or-none information processing has often been assumed as a basis for stage models and also as an important characteristic of nonlinear connectionist models; however, there has been little or no hard empirical evidence supporting the existence of this phenomenon. In search of such evidence, we applied speed-accuracy decomposition (Meyer et al., 1988), a technique for detecting partial response information, to the examination of the time-course of processing in a (Gestalt) insight-like task, namely, anagram solution. This task was chosen because the Gestalt psychologists conjectured that insight is a sudden, discrete phenomenon. Supporting this view, we found little or no evidence of partial information in two experiments, thereby providing what may be the strongest evidence to date for all-or-none processing.

Adult↗
PubMed1994

Concreteness effects in semantic processing: ERP evidence supporting dual-coding theory.

Dual-coding theory argues that processing advantages for concrete over abstract (verbal) stimuli result from the operation of 2 systems (i.e., imaginal and verbal) for concrete stimuli, rather than just 1 (for abstract stimuli). These verbal and imaginal systems have been linked with the left and right hemispheres of the brain, respectively. Context-availability theory argues that concreteness effects result from processing differences in a single system. The merits of these theories were investigated by examining the topographic distribution of event-related brain potentials in 2 experiments (lexical decision and concrete-abstract classification). The results were most consistent with dual-coding theory. In particular, different scalp distributions of an N400-like negativity were elicited by concrete and abstract words.

Adult↗
PubMed1994

Time-course studies of reality monitoring and recognition.

Two studies used a response-signal procedure to explore the time course of source-monitoring judgments about perceived and imagined events. Ss judged whether probe words corresponded to pictures that had previously been seen or imagined or were new. Old-new recognition accuracy grew to significant levels before reality-monitoring accuracy, supporting the notion that source monitoring requires more of or a different type of information than does old-new recognition. Also, source identification accuracy developed more quickly for imagined items than for perceived items. This difference in time-course functions is consistent with the idea that memories for perceived and imagined events differ in the relative amounts of various types of information they include (Johnson & Raye, 1981) and that these different types of information may revive or become available to source attribution mechanisms at different rates or may be differentially salient during reality monitoring.

Humans↗
PubMed1994

Semantic memory and the granularity of semantic relations: evidence from speed-accuracy decomposition.

In the present study we examined whether semantic relations are atomistic unitary associations, or are complex concepts consisting of a number of relational elements. The complexity of the ownership relation was assessed by combining a relation verification task ("Many people own [cars/comets]") with the speed-accuracy decomposition procedure (Meyer, Irwin, Osman, & Kounios, 1988). The latter permits one to determine whether subjects achieve their final state of response accuracy in a single, discrete all-or-none transition, or whether the relevant processes yield partial information representing intermediate states of knowledge. The rationale was that the retrieval of a unitary relational link from a classical associative network should be an all-or-none affair. In contrast, a set of relational elements need not be processed as a unitary bundle, thereby allowing partial response-information states. In two experiments, we found evidence of such partial information (i.e., sensitivity in units of d'), lending support to the notion that relations are complex. Furthermore, the results suggest that the accumulation of guessing sensitivity was linear over time, weighing against alternate theoretical interpretations.

Humans↗
PubMed1992

Structure and process in semantic memory: evidence from event-related brain potentials and reaction times.

Through scalp measurements of the electrical activity of the brain (event-related potentials, or ERPs) recorded while subjects verified the truth of sentences relating exemplars and categories (e.g., ALL DOGS ARE ANIMALS), inferences were made about aspects of semantic processing that were not directly reflected by overt responses. In particular, it is suggested that a negative ERP component that peaks about 400 ms after the onset of the sentence predicate (i.e., N400) is sensitive to structural aspects of semantic memory. The amplitude of this component was modulated by the relatedness of the subject and predicate terms, as well as the hierarchical level of both these terms, but was not sensitive to the truth value of a sentence.

Adult↗
PubMed1987

Structure and process in semantic memory: new evidence based on speed-accuracy decomposition.

Reaction-time and accuracy data obtained from studies of sentence verification have not been rich enough to answer certain important theoretical questions about structures and processes in human semantic memory. However, a new technique called speed-accuracy decomposition (Meyer, Irwin, Osman, & Kounios, 1986) may help solve this problem. The technique allows intermediate products of sentence verification to be analyzed more precisely. Three experiments with speed-accuracy decomposition indicate that verification processes produce useful partial information before they are completed. Such information appears to accumulate continuously at a rate whose magnitude depends on the degree of relatedness between semantic categories. This outcome is consistent with continuous computational (e.g., semantic-feature comparison) models of semantic memory. An analysis of reaction-time minima suggests that a discrete all-or-none search process may also contribute at least occasionally to sentence verification. Further details regarding the nature of these processes and the memory structures on which they operate can be inferred from additional results obtained through speed-accuracy decomposition.

Humans↗