Automatic Semantic Activation Research Articles

Verbal Learning and Memory in Early-Implanted, Prelingually Deaf Adolescent and Adult Cochlear Implant Users.

Purpose The purpose of this study was to investigate the information-processing strategies of early-implanted, prelingually deaf cochlear implant (CI) users with the California Verbal Learning Test-Second Edition (CVLT-II; Delis, Kramer, Kaplan, & Ober, 2000 ), a well-established normed measure of verbal learning and memory used in neuropsychological assessments of memory loss. Method Verbal learning and memory skills were compared in 20 older adolescent and young adult prelingually deaf long-term early-implanted CI users and their 24 normal hearing (NH) peers using the CVLT-II, a widely used multitrial free recall test of verbal learning and memory. Results On average, CI users recalled fewer words than their NH peers across the immediate, delayed, and cued recall trials of the CVLT-II but were comparable to their NH peers on yes/no recognition memory. CI users showed little evidence of semantic clustering of words during free recall but greater serial clustering compared to their NH peers, suggesting fundamental disturbances in automatic semantic activation of words from long-term memory. No differences were found in verbal memory between CI users and their NH peers on measures of retroactive interference and encoding/retrieval interactions. Performance on the 2nd word list of the CVLT-II (List B) and amount of semantic clustering of words during recall were correlated with sentence recognition in the CI group. Conclusion Study findings demonstrate significant differences in free recall performance and information-processing strategies that early-implanted, prelingually deaf CI users use to encode, organize, store, and retrieve spoken words in conventional verbal list learning paradigms, compared to their NH peers. Because verbal learning and memory are core foundational processes routinely used in daily functioning for a wide range of neurocognitive and language processing operations, these findings suggest potential domains for assessment and novel interventions to promote the development of optimal outcomes in prelingually deaf early-implanted long-term CI users.

The effect of associative strength on semantic priming in schizophrenia

The present research was designed to investigate the pattern of semantic priming in schizophrenia as a function of strength of association (or semantic distance between concepts in the semantic network). Thirty schizophrenia patients, without formal thought disorder, and twenty-nine healthy controls participated in a lexical decision task in which prime-target associative strength (strong, weak and not related) and stimulus-onset asynchrony (SOA: 250ms and 750ms) were manipulated. Patients and controls showed the same associative strength effect on RTs. In the short SOA condition priming effects were obtained for both strong and weak prime-target associative conditions. However in the long SOA priming was only significant for strongly associated pairs. This pattern of priming effects was similar in both groups, with higher priming on the short SOA and strong association conditions. Altogether results suggest that automatic semantic spreading activation is unimpaired in schizophrenia patients without formal thought disorder. These results are in line with the general evidence of impaired implicit priming observed only in patients with formal thought disorder. At the same time patients use context as controls to facilitate word processing. Finally, these findings evidence that, prime-target associative strength could moderate results in studies of semantic memory deficits in schizophrenia.

A brief review of three manipulations of the Stroop task focusing on the automaticity of semantic access

Since Stroop (1935), semantic access has been seen as automatic but today this is questioned, following minor modifications of the Stroop task. Besner, Stolz and Boutilier (1997) showed that coloring a single letter differently from the others and asking the participant to name the color of this letter, significantly reduced the Stroop effect. Huguet, Galvaing, Monteil and Dumas (1999) showed that another person’s presence during the test significantly reduced the Stroop effect. Raz, Shapiro, Fan and Posner (2002) showed a reduction in Stroop effect when hypnotized participants were told what would appear on the screen was not a word. These reductions suggest that semantic access of a word needs attentional resources, and is not automatic. This review summarizes recent results concerning reduction of the Stroop effect through the three manipulations mentioned above. The similarities and conflicts of these studies are illustrated. The conclusions suggest that these manipulations seem not to reduce or prevent automatic semantic activation, but rather reduce non-semantic task-relevant response competition. Using measures other than behavioral measures like Event-Related Potentials and a new definition of automaticity are proposed to understand better the different results cited.

Evidence of semantic clustering in letter-cued word retrieval

Letter-cued word fluency is conceptualized as a phonemically guided word retrieval process. Accordingly, word clusters typically are defined solely by their phonemic similarity. We investigated semantic clustering in two letter-cued (P and S) word fluency task performances by 315 healthy adults, each for 1 min. Singular value decomposition (SVD) and generalized topological overlap measure (GTOM) were applied to verbal outputs to conservatively extract clusters of high-frequency words. The results generally confirmed phonemic clustering. However, we also found considerable semantic/associative clusters of words (e.g., pen, pencil, and paper), and some words showed both phonemic and semantic associations within a single cluster (e.g., pair, pear, peach). We conclude that letter-cued fluency is not necessarily a purely phonemic word retrieval process. Strong automatic semantic activation mechanisms play an important role in letter-cued lexical retrieval. Theoretical conceptualizations of the word retrieval process with phonemic cues may also need to be reexamined in light of these analyses.

Semantic processing impairment in individuals with schizotypal personality disorder features: A preliminary event-related potential study

This study aimed to examine semantic processing features in individuals with and without schizotypal personality disorder (SPD) features. An implicit semantic task was used to examine the automatic spreading semantic activation process which is relatively free from the influence of attention. An explicit semantic task was used to examine the controlled semantic processing which requires high involvement of attention. Individuals with stable SPD features (n=17) were those who scored higher than 36 on the schizotypal personality questionnaire (SPQ) at two time points. Individuals with unstable SPD features (n=15) were defined as participants who scored higher than 36 at the baseline time point but lower than 36 at the second time point. Their performances in the two semantic tasks were then compared to 17 individuals without SPD features (scoring below 36 at both time points). Event-related potentials (ERP) were recorded when participants were performing the two tasks. Behavioral data, early ERP components and N400s were analyzed in each experiment. No between-group difference was observed in the implicit semantic task. In the explicit semantic task, the differences involved only the N400 component. When compared to the group without SPD features, participants with stable and unstable SPD features showed enhanced N400 effects (difference wave), while there was no difference between the two groups with SPD features. Moreover, the larger N400 effects were found to be due to less negative N400 amplitudes to related target words. These findings suggest that individuals with SPD features were impaired in processing of context-related stimuli. The inhibition function to contextually unrelated materials in participants with SPD features appeared intact.

Semantic Processing Disturbance in Patients with Schizophrenia: A Meta-Analysis of the N400 Component

BackgroundTheoretically semantic processing can be separated into early automatic semantic activation and late contextualization. Semantic processing deficits have been suggested in patients with schizophrenia, however it is not clear which stage of semantic processing is impaired. We attempted to clarify this issue by conducting a meta-analysis of the N400 component.MethodsTwenty-one studies met the inclusion criteria for the meta-analysis procedure. The Comprehensive Meta-Analysis software package was used to compute pooled effect sizes and homogeneity.ResultsStudies favoring early automatic activation produced a significant effect size of −0.41 for the N400 effect. Studies favoring late contextualization generated a significant effect size of −0.36 for the N400 effect, a significant effect size of −0.52 for N400 for congruent/related target words, and a significant effect size of 0.82 for the N400 peak latency.ConclusionThese findings suggest the automatic spreading activation process in patients with schizophrenia is very similar for closely related concepts and weakly or remotely related concepts, while late contextualization may be associated with impairments in processing semantically congruent context accompanied by slow processing speed.

The Influence of Dopamine on Automatic and Controlled Semantic Activation in Parkinson's Disease

Two semantic priming tasks, designed to isolate automatic and controlled semantic activation, were utilized to investigate the impact of dopamine depletion on semantic processing in Parkinson's disease (PD). Seven people with PD (tested whilst on and off levodopa medication) and seven healthy adults participated in the study. The healthy adult participants demonstrated intact automatic and controlled semantic activation. Aberrant controlled semantic activation was observed in the PD group on levodopa; however, automatic semantic activation was still evident. In contrast, automatic semantic activation was not evident in the PD group off levodopa. These results further clarify the impact of PD on semantic processing, demonstrating that dopamine depletion can cause disturbances in both automatic and controlled semantic activation.

Letter search and relatedness proportion: Further electrophysiological evidence for the automaticity of semantic activation

Automatic semantic activation was recently called a myth when the behavioral semantic priming effect was found to be subject to task demands. Semantic priming effects as measured by lexical decision times are typically reduced to the point of being absent when a letter search has to be performed on the prime word. It seems premature to draw any definite conclusion from this behavioral result as ERP recordings show that the same prime task leaves N400 priming effects unaffected. It is still a matter of debate whether N400 priming effects are generated chiefly by automatic or by cognitively controlled priming processes. In the present study we therefore recorded both lexical decision times and ERPs while we varied the ratio of related to unrelated prime–probe pairs (25% vs. 75% related) and thus manipulated the degree to which controlled mechanisms contribute to the semantic priming effect. Behavioral measures revealed reliable semantic priming effects only when RP was high and the influence of controlled processes hence increased. The modulation of the N400, however, provided clear-cut evidence of semantic processing at both RPs, indicating that semantic activation occurred even when RP was low and the involvement of controlled mechanisms was thus minimal.

Fast trial pacing in a lexical decision task reveals a decay of automatic semantic activation

We report an experiment showing that reducing attentional resources by presenting trials with a short, 400 ms intertrial interval (ITI) (a) did not affect semantic priming at a 160 ms prime-to-target stimulus-onset asynchrony (SOA), relative to a 2500 ms ITI, and (b) eliminated the priming that occurred at a 1200 ms SOA when the ITI was 2500 ms. However, the elimination of priming at the 1200 ms SOA occurred only when the relatedness proportion (RP, proportion of related primes and targets) was .25 and not when it was .75. We interpret these results as showing that attentional/strategic priming occurs with an RP as low as .25, but only when sufficient attentional resources are available. Equally important, this is the first direct evidence that automatic semantic activation decays within 1200 ms in the standard semantic-priming/lexical-decision paradigm when attentional resources are not being used to maintain the goal of sustaining prime activation. We further argue that the frequent occurrences of related primes and targets with a high RP serve as reminders to maintain that goal such that cognitive load does not reduce long-SOA priming when the RP is high.

Associative and orthographic neighborhood density effects in normal aging and Alzheimer’s disease.

A group of patients with Alzheimer's disease and a group of healthy elderly controls were tested with a lexical-decision task that included words with dense or sparse orthographic and associative neighborhoods to investigate whether there is automatic orthographic and semantic activation of related representations in these populations similar to that found with younger samples. Although some studies support the idea of deteriorated connections in semantic networks in Alzheimer's disease, other studies propose that the automatic spread of activation at lexicosemantic levels remains intact and that intergroup differences are a consequence of impaired retrieval or attentional deficits. In this study, participants responded to words with dense orthographic and associative neighborhoods faster than they did to words with sparse neighborhoods, providing evidence in favor of a preserved automatic spread of activation through intact orthographic and semantic representations. Furthermore, no differences were found between the two groups regarding the magnitude of the effects, although control participants responded significantly faster than patients.

With a letter-searched prime, boat primes float but swim and coat don’t: Further evidence for automatic semantic activation

Letter search (LS) on the prime typically eliminates semantic priming (swim-float) and orthographic/ phonological (O/P) priming (coat-float) but not morphological priming (marked-mark). However, LS on the prime does not reduce semantic priming for low-frequency targets (Tse & Neely, 2007). These findings suggest that semantic activation survives LS but decays during LS to a low level that can be detected only with sensitive measures, which are afforded by low-frequency targets and morphologically related primes and targets. In the present research, we show that LS on the prime results in 0 msec of semantic priming (e.g., swim-float) and 11 msec of O/P priming (e.g., coat-float), both of which are statistically null, whereas the LS semantic+O/P priming effect for primes and targets that do not share a morpheme (e.g., boat-float) is a robust 37 msec. Discussion focuses on the automaticity of semantic activation and whether morphological priming is mediated by (1) a morphemic representation that is separate from semantic representations or (2) activation combined from semantics and orthography/phonology.

Semantic activation and verbal working memory maintenance in schizophrenic thought disorder: insights from electrophysiology and lexical ambiguity.

We have examined language processing using ambiguous words (homographs like panel or toast) and rapid or slow presentation rates while recording event-related brain potentials (ERPs). Homographs allow for tracking the train of thought at points of lexical ambiguity and detecting modulation of associative threads by previous context. Rapid presentation rates stress automatic semantic activation, and slow rates stress controlled verbal working memory contextual modulation. In conjunction with reaction times and performance, ERPs allow for objective measurement of activity related to language processing from word presentation through overt behavioral response. Smaller N400 to related and unrelated items at short stimulus onset asynchronies (SOAs), the presence of a semantic bias, and large N400 to related and unrelated items at long SOAs are present in schizophrenia. We describe a model of initial semantic memory hyper-priming and subsequent decay of information in verbal working memory stores, the activation-maintenance model of schizophrenic thought disorder hypothesized to underlie the thought disorder in schizophrenia.

N400, the reference electrode, and the semantic activation in prime-task experiments: A reply to Dombrowski and Heil (2006)

In two recent papers, Heil et al. [Heil, M., Rolke, B., Pecchinenda, A., 2004. Automatic semantic activation is no myth: semantic context effects on the N400 in the Letter-Search task in the absence of response time effects. Psychol. Sci., 15 (12), 852–857] and Marí-Beffa et al. [Marí-Beffa, P., Valdés, B., Cullen, D.J.D., Catena, A., Houghton, G., 2005. ERP analyses of task effects on semantic processing from words. Cogn. Brain Res., 23, 293–305] found opposite ERP effects of semantic priming following letter search (as measured by the N400). Dombrowski and Heil [Dombrowski, J.H., Heil, M., 2006. Semantic activation, letter search and N400: a reply to Marí-Beffa, Valdés, Cullen, Catena and Houghton (2005). Brain Res., 1073–1074, 440–443] have argued that the N400 modulation associated to semantic priming found by Marí-Beffa et al. [Marí-Beffa, P., Valdés, B., Cullen, D.J.D., Catena, A., Houghton, G., 2005. ERP analyses of task effects on semantic processing from words. Cogn. Brain Res., 23, 293–305] is due to the use of electrode Cz as reference, rather than to the task manipulation being studied (letter search vs. categorisation). In the current article we argue that the conclusions of Dombrowski and Heil are mistaken and are due in part on a misreading of Marí-Beffa et al. [Marí-Beffa, P., Valdés, B., Cullen, D.J.D., Catena, A., Houghton, G., 2005. ERP analyses of task effects on semantic processing from words. Cogn. Brain Res., 23, 293–305]. We argue instead that the differences between the results of Heil et al. [Heil, M., Rolke, B., Pecchinenda, A., 2004. Automatic semantic activation is no myth: semantic context effects on the N400 in the Letter-Search task in the absence of response time effects. Psychol. Sci., 15 (12), 852–857] and Marí-Beffa et al. [Marí-Beffa, P., Valdés, B., Cullen, D.J.D., Catena, A., Houghton, G., 2005. ERP analyses of task effects on semantic processing from words. Cogn. Brain Res., 23, 293–305] are largely due to differences in experimental method and procedure, rather than to the technique used for the ERP analysis.

The influence of dopamine on semantic activation in Parkinson's disease: Evidence from a multipriming task.

Research has suggested that semantic processing deficits in Parkinson's disease (PD) are related to striatal dopamine deficiency. As an investigation of the influence of dopamine on semantic activation in PD, 7 participants with PD performed a lexical-decision task when on and off levodopa medication. Seven healthy controls matched to the participants with PD in terms of sex, age, and education also participated in the study. By use of a multipriming paradigm, whereby 2 prime words were presented prior to the target word, semantic priming effects were measured across stimulus onset asynchronies (SOAs) of 250 ms and 1,200 ms. The results revealed a similar pattern of priming across SOAs for the control group and the PD participants on medication. In contrast, within-group comparisons revealed that automatic semantic activation was compromised in PD participants when off medication. The implications of these results for the neuromodulatory influence of dopamine on semantic processing in PD are discussed.

Automatic semantic activation of embedded words: Is there a “hat” in “that”?

Participants semantically categorized target words that contain subsets (Experiment 1; e.g., target = hatch, subset = hat) or that are parts of supersets (Experiment 2; e.g., target = bee, superset = beer). In both experiments, the targets were categorized in a congruent condition (in which the subset–superset was associated with the same response, e.g., Does hatch refer to a human body part?) and an incongruent condition (in which the subset–superset was associated with a conflicting response, e.g., Does hatch refer to a piece of clothing?). Responses were slower and less accurate in the incongruent conditions, suggesting that subsets and supersets were processed to the level of meaning. Congruency effects occurred regardless of the position of the subset or superset (e.g., hatch, d rama, h owl), and in Experiment 1, were obtained for subsets that maintained (e.g., card) and changed their pronunciation (e.g., crown). Congruency effects were only found when the subsets were of higher frequency than the target. The implications for theories of word identification are discussed.

Summation of semantic priming effects in Parkinson’s Disease and healthy individuals

Parkinson’s Disease is characterized by a deficiency in striatal dopamine. Recent research has suggested that dopamine acts as a neuromodulator, which may alter the dynamics of automatic semantic activation. In particular, the research has suggested that Parkinson’s Disease (PD) patients may exhibit a delayed time course of spreading activation during automatic semantic priming tasks (e.g., Arnott, Chenery, Murdoch, & Silburn, 2001). Since delayed semantic processing has the potential to influence performance on various other language processing tasks, it represents an important area of research in PD. The use of multiple primes in a semantic priming task could extend recent findings by allowing the time course of semantic activation to be analysed more specifically.A recent semantic priming experiment by Balota and Paul (1996) investigated the effect of using multiple related prime words. The results revealed a summation of activation, whereby greater magnitudes of priming effects were found when two related primes were used, as opposed to when only the first or second prime word was related to the target.The aim of the present study was to investigate the time course of spreading activation during automatic semantic activation by using the multiple priming paradigm implemented by Balota and Paul (1996). If PD patients do experience a delayed time course of spreading activation, then summation priming would not be expected for the PD group, since sufficient spreading of activation would not have time to occur for both prime words.© 2003 Elsevier Inc.

Brain activity during automatic semantic priming revealed by event-related functional magnetic resonance imaging

Semantic priming occurs when a subject is faster in recognising a target word when it is preceded by a related word compared to an unrelated word. The effect is attributed to automatic or controlled processing mechanisms elicited by short or long interstimulus intervals (ISIs) between primes and targets. We employed event-related functional magnetic resonance imaging (fMRI) to investigate blood oxygen level dependent (BOLD) responses associated with automatic semantic priming using an experimental design identical to that used in standard behavioural priming tasks. Prime-target semantic strength was manipulated by using lexical ambiguity primes (e.g., bank) and target words related to dominant or subordinate meaning of the ambiguity. Subjects made speeded lexical decisions (word/nonword) on dominant related, subordinate related, and unrelated word pairs presented randomly with a short ISI. The major finding was a pattern of reduced activity in middle temporal and inferior prefrontal regions for dominant versus unrelated and subordinate versus unrelated comparisons, respectively. These findings are consistent with both a dual process model of semantic priming and recent repetition priming data that suggest that reductions in BOLD responses represent neural priming associated with automatic semantic activation and implicate the left middle temporal cortex and inferior prefrontal cortex in more automatic aspects of semantic processing.

Lexical Decision in Parkinsons Disease: A Reply to Brown, McDonald, and Spicer (1999)

Recent semantic priming investigations in Parkinsons disease (PD) employed variants of Neelys (1977) lexical decision paradigm to dissociate the automatic and attentional aspects of semantic activation (McDonald, Brown, Gorell, 1996; Spicer, Brown, Gorell, 1994). In our earlier review, we claimed that the results of Spicer, McDonald and colleagues normal control participants violated the two-process model of information processing (Posner Snyder, 1975) upon which their experimental paradigm had been based (Arnott Chenery, 1999). We argued that, even at the shortest SOA employed, key design modifications to Neelys original experiments biased the tasks employed by Spicer et al. and McDonald et al. towards being assessments of attention-dependent processes. Accordingly, we contended that experimental procedures did not speak to issues of automaticity and, therefore, Spicer, McDonald and colleagues claims of robust automatic semantic activation in PD must be treated with caution.

Semantic priming by pictures and words in the cerebral hemispheres

In order to determine whether pictures would act as more effective semantic primes than words in the right cerebral hemisphere, automatic semantic activation in intact hemispheres was studied with primed GO–NOGO lexical decision tasks by presenting word–word and picture–word pairs to the left visual field (right hemisphere) or to the right visual field (left hemisphere). Response times in Experiment 1 showed that categorically related targets (e.g., TABLE–BED) were primed only in the right visual field after both word and picture primes. Experiment 2 found that picture primes activated the representations of the corresponding written names in both visual fields. These observations suggest that the range of automatic semantic activation is larger in the left than in the right hemisphere. The results implicate that semantic categories may be organized in a different fashion in the left than the right hemisphere.

What is Right and What is Left in Semantic Processing: A Reply to Chiarello

We welcome this opportunity to discuss further our study (Koivisto & Laine, 2000, this issue) and the theoretical conclusions we presented as a model on hemispheric mechanisms in semantic processing. The model put forth claims that when semantic priming occurs within the left visual field/right hemisphere (LVF/RH), it is attributable to postlexical semantic integration, and when priming can be attributed to automatic semantic activation, it only occurs within the right visual field/left hemisphere (RVF/LH). Chiarello (2000, this issue) argues in her commentary that (1) our data supporting this account are weak, (2) our model cannot accommodate the data, and (3) the support for our account from prior literature is not as strong as we claimed.