Indirect Semantic Priming Research Articles

Direct and indirect semantic priming with neutral and emotional words in schizophrenia: Relationship to delusions

Introduction. Evidence is accumulating that suggests that semantic networks are abnormal in schizophrenia. Methods. To investigate this further, we examined priming in 42 schizophrenics and 28 normal controls on a lexical decision task involving three different prime-target conditions all at 700 ms stimulus onset asynchrony (SOA): directly semantically related, indirectly semantically related, and unrelated; and three types of emotional pairings: positive, negative, and neutral. Two schizophrenic groups were compared: nondeluded (no current delusions) and deluded. Results. Schizophrenic patients did not demonstrate significant direct priming overall, whereas controls did. However, when material was examined according to emotional pairing, the controls and deluded subjects demonstrated significant priming to neutral word pairs. Neither schizophrenic group showed direct priming with positive and negative word pairings, the deluded subjects showing inhibition of priming with negative stimuli. Controls failed to show direct priming with negative stimuli. Indirect priming was obtained in all groups. The absence of direct priming and indirect priming with negative material in deluded subjects was particularly striking. The results point to quantitative and qualitative abnormalities in semantic networks in schizophrenia. Conclusions. We propose that delusions may be the result of intact, unusual (indirect) associations in contrast to poorer normal (semantic) associations; a particular bias being shown toward material of a negative valence.

Electrophysiological correlates of direct versus indirect semantic priming in normal volunteers

The N400 component of event related potentials (ERP) was studied in 27 right-handed healthy subjects in a speeded lexical decision task. The semantic distance between primes (always words) and targets (50% words, 50% non-words) was systematically varied. Prime–target relations included directly related words (hen–egg), indirectly related words (lemon–sweet), and non-related words (sofa–wing). ERPs were recorded from 20 scalp electrodes positioned according to the international 10–20 system. The N400 reflected semantic distance with the most negative and latest N400 peak in the non-related condition, the least negative and earliest N400 peak in the direct condition and the peak in the indirect condition in-between. Hence, N400 priming effect in the indirect condition was obtained in the absence of strong sentential constraints and even though the mediating word was physically not present.

Right Hemisphere Activation during Indirect Semantic Priming: Evidence from Event-Related Potentials

Healthy subjects performed a lexical decision task in a semantic priming paradigm while event-related potentials (ERPs) were recorded from 64 channels. Semantic distance between prime and target was varied by including directly, indirectly, and nonrelated word pairs. At centro-parietal electrodes an N400 to nonrelated pairs was elicited bilaterally which was sensitive only to direct, but not to indirect semantic priming. These N400 priming effects were mirrored by the RT data. At inferior fronto-temporal sites directly related words showed ERP priming effects over both hemispheres. However, indirectly related words only elicited ERP priming effects over the right hemisphere. These results support the hypothesis that the right hemisphere semantic system is involved in processing of remote semantic information.

Lateralised semantic and indirect semantic priming effects in people with schizophrenia.

In schizophrenia, disturbances in the development of physiological hemisphere asymmetry are assumed to play a pathogenetic role. The most striking difference between hemispheres is in language processing. The left hemisphere is superior in the use of syntactic or semantic information, whereas the right hemisphere uses contextual information more effectively. Using psycholinguistic experimental techniques, semantic associations were examined in 38 control subjects, 24 non-thought-disordered and 16 thought-disordered people with schizophrenia, for both hemispheres separately. Direct semantic priming did not differ between the hemispheres in any of the groups. Only thought-disordered people showed significant indirect semantic priming in the left hemisphere. The results support: (a) a prominent role of the right hemisphere for remote associations; (b) enhanced spreading of semantic associations in thought-disordered subjects; and (c) disorganisation of the functional asymmetry of semantic processing in thought-disordered subjects.

Electrical brain activity reflecting semantic memory access in normal volunteers and schizophrenic patients: evidence from indirect semantic priming

Electrical brain activity reflecting semantic memory access in normal volunteers and schizophrenic patients: evidence from indirect semantic priming

Electrical brain activity reflecting semantic memory access in normal volunteers and schizophrenic patients: Evidence from indirect semantic priming

Electrical brain activity reflecting semantic memory access in normal volunteers and schizophrenic patients: Evidence from indirect semantic priming

The electrophysiology of semantic and indirect semantic priming in normal controls and schizophrenic patients

Background: The present study was designed to assess, using event-related potentials, whether aberrant semantic processing reported in schizophrenia results from primary semantic overactivation or contextual dysregulation.Methods: The visual event-related brain potentials were compared between 9 schizophrenic subjects and 16 normal control subjects performing two kinds of semantic categorization tasks with different nontarget stimuli: 1) nontargets comprising words, pseudowords, and unpronounceable foreign letters and 2) nontargets comprising initial presenting words, immediate repetition words, and delayed repetition words.Results: Schizophrenic subjects showed no evidence suggestive of a greater negative potential associated with words and pseudowords, but they did show a lack of amplitude change associated with immediately repeated words relative to that in control subjects.Conclusions: These results suggest that aberrant semantic activation in schizophrenia results mainly from a failure to utilize information from preceding words or context, and could explain the increased N400 to the congruent or related words recently reported in this disease.

L-DOPA increases signal-to-noise ratio in semantic networks: Evidence from indirect semantic priming in normal subjects

L-DOPA increases signal-to-noise ratio in semantic networks: Evidence from indirect semantic priming in normal subjects

Associative semantic network dysfunction in thought-disordered schizophrenic patients: Direct evidence from indirect semantic priming

The characteristics of the spread of semantic activation in associative networks in normal subjects, thought-disordered (TD) and nonthought-disordered (NTD) schizophrenic patients with respect to time and semantic distance are examined. Direct and indirect semantic priming effects at two stimulus onset asynchronies (SOA) in a lexical decision task reveal that semantic associations spread further and faster in TD schizophrenic patients than in normal controls and in NTD schizophrenic patients. From a methodological point of view, indirect semantic priming at short prime-target intervals appears to be the best indicator of associative network dysfunction. The findings are discussed within the framework of current research on the effect of dopamine on the signal-to-noise ratio in cortical neural networks. Data suggest that semantic associative memory operates at a comparatively lower signal-to-noise ratio in thought-disordered schizophrenic patients.

Indirect semantic priming in schizophrenic patients

Schizophrenic patients and normal controls performed a lexical decision task involving the recognition of words which were preceded (primed) by either associated, indirectly associated, or non-associated words. In contrast to normal control subjects who showed no indirect semantic priming effect at an inter-stimulus interval (ISI) of 0 ms, a trend towards such an indirect semantic priming effect was found in schizophrenic patients. With a longer ISI of 500 ms, an indirect semantic priming effect was obtained in both groups. In the framework of network models of semantic memory, the results are interpreted as further evidence for an increase in activation or decrease in inhibition in the spreading of associational activation in schizophrenic patients.