Neural Correlates of Causal Inferences and Semantic Priming in People with Williams Syndrome: An fMRI Study

This study aimed at examining the ability of causal inferences and semantic priming of people with Williams syndrome (WS). Previous studies pointed out that people with WS showed deviant sentence comprehension, given advantageous lexical semantics. This study investigated the impairment in connecting words in the semantic network by using neuroimaging techniques to reveal neurological deficits in the contextual integration of people with Williams syndrome. Four types of word pairs were presented: causal, categorical, associative, and functional. Behavioural results revealed that causal word pairs required heavier cognitive processing than functional word pairs. Distinct neural correlates of semantic priming confirmed atypical semantic linkage and possible cause of impairment of contextual integration in people with WS. The findings of normal behaviours and atypical neural correlates in people with WS provide evidence of atypical development resulted from early gene mutations

BEHAVIORAL AND ELECTROPHYSIOLOGICAL INVESTIGATIONS OF SEMANTIC PROCESSING IN SKILLED AND LESS-SKILLED COMPREHENDERS

Theorists of reading comprehension failure are split between two groups: those that posit low-level word reading skills and phonological awareness as underlying factors of poor comprehension ability and those that consider poor comprehension as partially independent of these low-level skills. Several studies with children have now demonstrated that poor comprehenders with adequate decoding skills make up a small but significant proportion of poor readers. One promising hypothesis posits that semantic processing deficits underlie these children's comprehension difficulties. This hypothesis was supported by findings that demonstrated less-skilled comprehenders to show poorer than average performance on a variety of semantic tasks. In order to test whether these findings would generalize to adult poor comprehenders, we evaluated the dissociability of high-level and low-level skills in adults. In addition, we evaluated whether adult less-skilled comprehenders (with adequate decoding abilities) have semantic processing difficulties. A PCA compared the reading skills of large group of college aged readers and found that high level skills such as reading comprehension and vocabulary were partly dissociable from low-level reading skills such as decoding ability. Furthermore, in order to evaluate the semantic processing deficit hypothesis, adult skilled and less-skilled comprehenders were compared on several behavioral and electrophysiological tests of semantic and phonological processing. The findings from these studies revealed that less-skilled comprehenders generated fewer semantic associates in a verbal fluency task and showed reduced categorical priming in an automatic semantic priming task. Additionally, electrophysiological records of less-skilled comprehenders differed from skilled readers during a semantic processing task but no during a phonological processing task. Taken together these findings provide evidence that supports semantic knowledge/semantic processing differences between skilled and less-skilled comprehenders. Implications of these findings are discussed within the construct of an experience based model of semantic knowledge acquisition

Emotion words and categories: evidence from lexical decision

We examined the categorical nature of emotion word recognition. Positive, negative, and neutral words were presented in lexical decision tasks. Word frequency was additionally manipulated. In Experiment 1, "positive" and "negative" categories of words were implicitly indicated by the blocked design employed. A significant emotion–frequency interaction was obtained, replicating past research. While positive words consistently elicited faster responses than neutral words, only low frequency negative words demonstrated a similar advantage. In Experiments 2a and 2b, explicit categories ("positive," "negative," and "household" items) were specified to participants. Positive words again elicited faster responses than did neutral words. Responses to negative words, however, were no different than those to neutral words, regardless of their frequency. The overall pattern of effects indicates that positive words are always facilitated, frequency plays a greater role in the recognition of negative words, and a "negative" category represents a somewhat disparate set of emotions. These results support the notion that emotion word processing may be moderated by distinct systems

A developmental study of the role of category information in word identification

The studies reported here were generated out of the hypothesis that category information about a word is initially activated prior to identification of the word. Three experiments investigated the role of category information in word identification by 3rd graders, 6th graders, and adults using a serial two-choice classification paradigm. Semantic properties of lists of words and target search instructions were varied to assess the facilitation of the categorical homogeneity of the nontarget words on target word identification. Experiments 1 and 2 required subjects to identify words as exemplars or not of a predefined category as soon as possible. The target words were in lists of categorically homogeneous and categorically heterogeneous nontarget words. Nontarget categories were different from target categories

Manipulations of List Type in the DRM Paradigm: A Review of How Structural and Conceptual Similarity Affect False Memory

The use of list-learning paradigms to explore false memory has revealed several critical findings about the contributions of similarity and relatedness in memory phenomena more broadly. Characterizing the nature of “similarity and relatedness” can inform researchers about factors contributing to memory distortions and about the underlying associative and semantic networks that support veridical memory. Similarity can be defined in terms of semantic properties (e.g., shared conceptual and taxonomic features), lexical/associative properties (e.g., shared connections in associative networks), or structural properties (e.g., shared orthographic or phonological features). By manipulating the type of list and its relationship to a non-studied critical item, we review the effects of these types of similarity on veridical and false memory. All forms of similarity reviewed here result in reliable error rates and the effects on veridical memory are variable. The results across a variety of paradigms and tests provide partial support for a number of theoretical explanations of false memory phenomena, but none of the theories readily account for all results

The Effects of Blocked and Random Word Lists on the Production of False Memories

This study separated participants into four different conditions based on a 2 (blocked or random study trials) x 2 (blocked or random test trials) between-subjects design. Using the Deese-Roediger-McDermott (DRM) paradigm the researcher investigated whether or not false memories were produced at the time of study or the time of test. According to the paradigm, participants who view a series of categorical words (mad, fear, hate, rage, temper) are thought to semantically associate critical lures (anger), as a part of the list presented, more frequently than participants who see a string of unrelated terms. The production of false memory is commonly accredited to the priming effect and the relationships among categorical terms. The current study explored whether manipulating blocked versus random word lists had an effect on false memory rates and further examined the conditions under which false memories are produced, in order to gain a better understanding of the phenomenon. Participants\u27 responses were assessed based on their recall under either blocked or random conditions in both the study and test phases. Using measures of recognition and reaction time (RT), the results indicate that false memories are created primarily during original study and not during · the test of recognition. However, although the highest rates of false memories occurred during the blocked-study condition, the fastest reaction times for false memories were seen during blocked-test. These findings can contribute to the theoretical understanding of the origin of false memory. After comparing false memory rates and reaction times, concluding whether or not the mind exclusively produces these memories during the encoding process has yet to be determined

Types of interference and their resolution in monolingual language production

There is accumulating evidence that speakers recruit inhibitory control to manage the conflicting demands of online language production, e.g., when selecting from among co-activated representations during object naming or when suppressing alternative competing terms in referential language use. However, little is known about the types of conflict resolution mechanisms underlying the production processes. The aim of this research was to assess the relative contribution of various forms of interference arising at different stages of information processing as well as their control to single- and multi-word utterance production. The systematic review of picture-word interference (PWI) studies (Study 1) was conducted to trace the origins of semantic context effects in order to address the question of whether spoken word production can be seen as a competitive process. The various manipulations of PWI task parameters in the reviewed studies produced a mixture of findings that were either contradictory, unable to discriminate between the rival theories of lexical access, or of questionable validity. Critically, manipulations of distractor format and of whole-part relations with varied association strength produced sufficiently strong evidence to discount post-lexical non-competitive accounts as the dominant explanations for observed interference effects, constraining their locus to early rather than late processing stages. The viability of competitive hypotheses was upheld; however, this is contingent on the relative contribution of pre-lexical processes, which remains to be confirmed by future research. The relative contribution of different conflict resolution mechanisms (measured by the anti-saccade, arrow flanker and Simon arrow tasks) to object naming under prepotent (the PWI task) and underdetermined competition (picture naming task with name agreement, NA, manipulation) was further investigated in Study 2, while Study 3 extended the notion of separability of the inhibitory processes to grammatical encoding (grammatical voice construction and number agreement computation). In Study 2, only the flanker effect was a significant predictor of the PWI but not NA effect, while the remaining inhibitory measures made no significant contribution to either the PWI or NA effect. Participants with smaller flanker effects, indicative of better resolution of representational conflict, were faster to name objects in the face of competing stimuli. In Study 3, only utterance repairs were reliably predicted by the flanker and anti-saccade effects. Those who resolved representational conflict or inhibited incorrect eye saccades more efficiently were found to self-correct less often during online passive voice construction than those with poorer resolution of inhibition at the representational and motor output level. No association was found between the various inhibitory measures and subject-verb agreement computation. The negative priming study with novel associations (Study 4) was an attempt at establishing the causal link between inhibition and object naming, and specifically whether inhibition that is ostensibly applied to irrelevant representations spreads to its associatively related nodes. Response times to the associated probe targets that served as distractors in previous prime trials were no different than response times to non-associated probe targets. Possible explanations are discussed for the lack of the associative negative priming effect. The studies described here implicate two types of interference resolution abilities as potential sources of variability in online production skills, with the underlying assumption that better resolution of conflict at the representational and motor output level translates to faster naming and more fluent speech. There is insufficient evidence to determine whether the representational conflict is lexical or conceptual in nature, or indeed whether it is inhibitory in the strict sense. It also remains to be established whether interference that likely ensues at the response output stage is due to some criterion checking process (self-monitoring), recruitment of an inhibitory mechanism (response blocking) or both

Understanding person acquisition using an interactive activation and competition network

Face perception is one of the most developed visual skills that humans display, and recent work has attempted to examine the mechanisms involved in face perception through noting how neural networks achieve the same performance. The purpose of the present paper is to extend this approach to look not just at human face recognition, but also at human face acquisition. Experiment 1 presents empirical data to describe the acquisition over time of appropriate representations for newly encountered faces. These results are compared with those of Simulation 1, in which a modified IAC network capable of modelling the acquisition process is generated. Experiment 2 and Simulation 2 explore the mechanisms of learning further, and it is demonstrated that the acquisition of a set of associated new facts is easier than the acquisition of individual facts in isolation of one another. This is explained in terms of the advantage gained from additional inputs and mutual reinforcement of developing links within an interactive neural network system. <br/

Semantic memory

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