Contextual priming in semantic anomia: a case study

The present case continues the series of anomia treatment studies with contextual priming (CP), being the second in-depth treatment study conducted for an individual suffering from semantically based anomia. Our aim was to acquire further evidence of the facilitation and interference effects of the CP treatment on semantic anomia. Based on the results of the study of , our hypothesis before the treatment was that our participant would show short-term interference and at most modest and short-term benefit from treatment. To acquire such evidence would not only be important for the choice of anomia treatment methods in individual patients, but would also prompt further development of the CP method. The CP technique used for our participant included cycles of repeating and naming items in three contextual conditions (semantic, phonological, and unrelated). As predicted, the overall improvement of naming was modest and short-term. Interestingly, the contextual condition that corresponded with the nature of our patient's underlying naming deficit (semantic) elicited immediate interference in the form of contextual naming errors, as well as short-term improvement of naming. Based on this and a recent study by , it appears that despite short-term positive effects, in its current form the CP treatment is not sufficient for those aphasics who have a semantic deficit underlying their anomia. The possible mechanism and directions for future research are discussed.     

A case study of anomaly detection: Shallow semantic processing and cohesion establishment

Although the establishment of a coherent mental representation depends on semantic analysis, such analysis is not necessarily complete. This is illustrated by failures to notice the anomaly in questions such as, “When an airplane crashes, where should the survivors be buried?” Four experiments were carried out to extend knowledge of what determines the incidental detection of the critical item. Detection is a function of the goodness of global fit of the item (Experiments 1 and 2) and the extent to which the scenario predicts the item (Experiment 3). Global good fit appears to result in shallow processing of details. In Experiment 4, it is shown that if satisfactory coherence can be established without detailed semantic analysis, through the recruitment of suitable information from a sentence, then processing is indeed shallow. The studies also show that a text is not understood by first producing a local semantic representation and then incorporating this into a global model, and that semantic processing is not strictly incremental.     

Sex differences in semantic language processing: a functional MRI study

Predictions based on two models of sex differences in cerebral organization of language were compared by examining fMRI patterns of 10 females and 9 males during a semantic processing task. Both groups displayed activation of left inferior frontal gyrus (IFG), left superior temporal gyrus (STG), and cingulate. Females, but not males, showed bilateral IFG and STG activation. Further analyses revealed females had less diffuse left activation and greater right posterior temporal and insula region activation than males. Results support both an interhemispheric and an intrahemispheric model of sex differences in language, suggesting that the models may not be mutually exclusive.     

Effects of speed of word processing on semantic access: the case of bilingualism

Bilingual speakers generally manifest slower word recognition than monolinguals. We investigated the consequences of the word processing speed on semantic access in bilinguals. The paradigm involved a stream of English words and pseudowords presented in succession at a constant rate. English-Welsh bilinguals and English monolinguals were asked to count the number of letters in pseudowords and actively disregard words. They were not explicitly told that pairs of words in immediate succession were embedded and could either be semantically related or not. We expected that slower word processing in bilinguals would result in semantic access indexed by semantic priming. As expected, bilinguals showed significant semantic priming, indexed by an N400 modulation, whilst monolinguals did not. Moreover, bilinguals were slower in performing the task. The results suggest that bilinguals cannot discriminate between pseudowords and words without accessing semantic information whereas monolinguals can dismiss English words on the basis of subsemantic information.     

Priming of semantic autobiographical knowledge: a case study of retrograde amnesia

The case of a 36-year-old man who suffers dense retrograde and anterograde amnesia as a result of closed-head injury that caused extensive damage to his left frontal-parietal and right parieto-occipital lobes is described. Patient K.C. has normal intelligence and relatively well-preserved perceptual, linguistic, short-term memory, and reasoning abilities. He possesses some fragmentary general knowledge about his autobiographical past, but he does not remember a single personal event or happening from any time of his life. He has some preserved expert knowledge related to the work he did for 3 years before the onset of amnesia, although he has no personal recollections from that period. Some features of K.C.'s retrograde amnesia can be interpreted in terms of the distinction between episodic and semantic memory, and in terms of the distinction between episodic and semantic autobiographical knowledge. K.C.'s semantic knowledge, but not his episodic knowledge, showed progressive improvement, or priming, in the course of the investigation.     

Attention and semantic processing during speech: an fMRI study

This fMRI study was conducted to investigate whether language semantics is processed even when attention is not explicitly directed to word meanings. In the “unattended” condition, the subjects performed a visual detection task while hearing semantically related and unrelated word pairs. In the “phoneme” condition, the subjects made phoneme judgements between prime and target words, and in the “word” condition, they indicated whether the words in each word pair were semantically related or unrelated. In the word condition, stronger activity was obtained for unrelated than related words in the superior temporal gyrus/sulcus (STG/STS), lingual/fusiform gyri and cuneus, whereas in the phoneme condition no such effect was observed. However, during the unattended condition, stronger activity was found in the right STG. Our results suggest that both semantic judgement of word pairs and their passive hearing activate the same neural networks but this activation is more restricted in the passive hearing.     

Sentence processing strategies in healthy seniors with poor comprehension: an fMRI study

We used fMRI to examine patterns of brain recruitment in 22 healthy seniors, half of whom had selective comprehension difficulty for grammatically complex sentences. We found significantly reduced recruitment of left posterolateral temporal [Brodmann area (BA) 22/21] and left inferior frontal (BA 44/6) cortex in poor comprehenders compared to the healthy seniors with good sentence comprehension, cortical regions previously associated with language comprehension and verbal working memory, respectively. The poor comprehenders demonstrated increased activation of left prefrontal (BA 9/46), right dorsal inferior frontal (BA 44/6), and left posterior cingulate (BA 31/23) cortices for the grammatically simpler sentences that they understood. We hypothesize that these brain regions support an alternate, nongrammatical strategy for processing complex configurations of symbolic information. Moreover, these observations emphasize the crucial role of the left perisylvian network for grammatically guided sentence processing in subjects with good comprehension.     

Configural face processing: a meta-analytic survey

In the field of face processing, the configural hypothesis is defended by many researchers. It is often claimed that this thesis is robustly supported by a large number of experiments exploring the face-inversion effect, the composite face effect, the face superiority effect, and the negative face effect. However, this claim is generally based on a rudimentary and approximate vote-counting approach. In this paper, I use meta-analyses to examine the relevant literature in more depth. The analysis supports the vote-counting argument.     

The semantic/episodic distinction: The case for social information processing

The directed-forgetting paradigm was used in order to dissociate episodic from semantic processes in an impression formation task. Results demonstrate that incongruent behaviors are more prone to manipulations that disrupt episodic memory, whereas congruent behaviors are unaffected by such manipulations. The results suggest that the distinction between episodic and semantic memory processes is central for the understanding of social information processing. An explanation is put forward according to which the incongruency effect, a signature effect of impression formation, is due to an episodic encoding advantage for incongruent behaviors because of their semantically isolated nature, and their impoverished semantic encoding.     

The role of eyes in early face processing: a rapid adaptation study of the inversion effect

The current study employed a rapid adaptation procedure to test the neuronal mechanisms of the face inversion effect (FIE) on the early face-sensitive event-related potential (ERP) component N170. Five categories of face-related stimuli (isolated eyes, isolated mouths, eyeless faces, mouthless faces, and full faces) and houses were presented in upright and inverted orientations as adaptors for inverted full face test stimuli. Strong adaptation was found for all face-related stimuli except mouths. The adaptation effect was larger for inverted than upright stimuli, but only when eyes were present. These results underline an important role of eyes in early face processing. A mechanism of eye-dependent orientation sensitivity during the structural encoding stage of faces is proposed.     

Semantic access processing in a supra-modal deficit: a single case study

The case is presented of a semantic dementia patient, who shows a deficit selective for (i) conceptual class (living things), (ii) attribute processing (visual features) and affecting (iii) input-output modalities at the same processing stage (matching stored representation to attributes). The first experimental part aims at exploring the specific stage/process at which semantic knowledge breaks down through multi-modality tasks, devised to tap different levels within the semantic elaboration flow. The second focuses on the differences between category vs. attribute knowledge across various modalities. The core nature of the patient's deficit is investigated through a close comparison of her damage to a specific processing stage across modalities in the light of her class and attribute-specific impairment. The complex pattern of findings is discussed according to current theoretical accounts of semantic memory organization. Finally, the relevance of the adoption of a broad perspective when dealing with semantic memory impairments is highlighted.     

Recognising the ageing face: the role of age in face processing.

The effect of age-induced changes on face recognition were investigated as a means of exploring the role of age in the encoding of new facial memories. The ability of participants to recognise each of six previously learnt faces was tested with versions which were either identical to the learnt faces, the same age (but different in pose and expression), or younger or older in age. Participants were able to cope well with facial changes induced by ageing: their performance with older, but not younger, versions was comparable to that with faces which differed only in pose and expression. Since the large majority of different age versions were recognised successfully, it can be concluded that the process of recognition does not require an exact match in age characteristics between the stored representation of a face and the face currently in view. As the age-related changes explored here were those that occur during the period of growth, this in turn implies that the underlying structural physical properties of the face are (in addition to pose and facial expression) invariant to a certain extent.     

Interpretation-based processing: a unified theory of semantic sentence comprehension

We present interpretation-based processing—a theory of sentence processing that builds a syntactic and a semantic representation for a sentence and assigns an interpretation to the sentence as soon as possible. That interpretation can further participate in comprehension and in lexical processing and is vital for relating the sentence to the prior discourse. Our theory offers a unified account of the processing of literal sentences, metaphoric sentences, and sentences containing semantic illusions. It also explains how text can prime lexical access. We show that word literality is a matter of degree and that the speed and quality of comprehension depend both on how similar words are to their antecedents in the preceding text and how salient the sentence is with respect to the preceding text. Interpretation-based processing also reconciles superficially contradictory findings about the difference in processing times for metaphors and literals. The theory has been implemented in ACT-R [Anderson and Lebiere, The Atomic Components of Thought, Lawrence Erlbaum Associates Publishers, Mahwah, NJ, 1998].     

Prosopagnosia: a case study involving problems in processing configural information

An ongoing issue in face recognition research is whether holistic face processing relies on the segregation of local discrete facial parts. Evidence in favor of the holistic-plus-parts view stems from a recent study reported by Arguin and Saumier (1999), who show that the priming effects of individual facial parts (i.e., eyes, nose, mouth, orcontour) depends on the presence of configural information and that the magnitude of priming augments as the number of facial parts serving as primes increase. The present study demonstrates that these global processing effects are absent in a prosopagnosic patient (A.R.), who shows no priming from single face parts and a linear increase in the magnitude of priming as a function of the number of parts presented. These findings indicate that A.R. is incapable of integrating individual facial parts into a global facial configuration ant that this is likely at the root of her prosopagnosia.     

A comparison of sentence- and discourse-level semantic processing: an ERP study

Eighteen subjects listened to sentences ending with semantically congruent or incongruent words. Each congruent sentence was embedded at the end of a short story so that the final word was semantically acceptable at the sentence level but incongruent in terms of discourse context. The same stories were also presented with congruent endings. Auditory ERPs elicited by the final words in these sentences and stories were compared. Both sentence- and discourse-level semantic integration were associated with N400 and Late Positive Component (LPC) effects in addition to a new component, P550. Local and global semantic processing, although evoking the same components, were characterized by differential effects on ERP amplitudes according to the amount of text integrated and its congruence. These results indicate similar cognitive processes of context build up, underlying sentence- and discourse-semantic processing.     

The first 100 milliseconds of a face: on the microgenesis of early face processing

Face recognition involves both processing of information relating to features (e.g., eyes, nose, mouth, hair, i.e., featural processing), as well as the spatial relation between these features (configural processing). In a sequential matching task, participants had to decide whether two faces that differed in either featural or relational aspects were identical or different. In order to test for the microgenesis of face recognition (the development of processing onsets), presentation times of the backward-masked target face were varied (32, 42, 53, 63, 74, 84, or 94 msec.). To test for specific processing onsets and the processing of different facial areas, both featurally and relationally modified faces were manipulated in terms of changes to one facial area (eyes or nose or mouth), two, or three facial areas. For featural processing, an early onset for the eyes and mouth was at 32 msec. of presentation time, but a late onset for the nose was detected. For relationally differing faces, all onsets were delayed.     

Sentence processing in Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative condition that is associated with the depletion of dopamine (DA)-containing neurons in specific brain regions. This article reviews one consequence of this defect-sentence comprehension difficulty in nondemented patients with PD. The first section describes the pattern of cognitive deficits seen in patients with PD, focusing specifically on their difficulties with language processing. Subsequent sections relate the profile of cognitive impairments in PD to studies investigating compromised DA metabolism in fronto-striatal brain regions. The findings suggest that the sentence comprehension deficit in PD is due in large part to limitations in the strategic distribution of cognitive resources such as selective attention that contribute to the processing of complex material. The physiological basis for this deficit appears to be associated with the disruption of a fronto-striatal cerebral network that is compromised following degradation of the DA projection system.     

Automatic and controlled semantic processing: a masked prime-task effect

A classical definition of automaticity establishes that automatic processing occurs without attention or consciousness, and cannot be controlled. Previous studies have demonstrated that semantic priming can be reduced if attention is directed to a low-level of analysis. This finding suggests that semantic processing is not automatic since it can be controlled. In this paper, we present two experiments that demonstrate that semantic processing may occur in the absence of attention and consciousness. A negative semantic priming effect was found when a low-level prime-task was required and when a masked lexical decision prime-task was performed (Experiment 1). This paper also discusses the limitations of the inhibitory mechanism involved in negative semantic priming effect.