Psychopathy and verbal emotion processing in non-incarcerated males

Incarcerated males who score high on personality measures of psychopathy are reported to be less efficient than other incarcerated males in processing emotionally laden stimuli. In this study, we evaluated whether an emotion deficit is also present in non-incarcerated higher functioning males who score high on psychopathy personality measures. A sample of male university students was screened for psychopathic personality, and two subsamples, those who scored high or low on global psychopathy, participated in a series of language processing tasks designed to assess verbal emotion processing. Unlike previous studies of emotion processing in the verbal domain, stimuli also systematically varied in abstractness. The results showed that participants scoring high in psychopathy were less efficient than those scoring low in psychopathy in processing negatively valenced words, across all levels of word abstractness. The results extend previous accounts of emotional processing deficits in individuals with psychopathic personality to a relatively high-functioning non-incarcerated sample.     

Effects of processing speed on cerebral asymmetry for left- and right-oriented faces

A free-vision chimeric facial emotion judgment task and a tachistoscopic face-recognition reaction time task were administered to 20 male right-handed subjects. The tachistoscopic task involved judgments of whether a poser in the centrally presented full-face photograph was the same or different poser than in a profile photograph presented in the left or right visual field (LVF, RVF). The free-vision task was that used by J. Levy, W. Heller, M. Banich, and L. Burton (1983, Brain and Cognition, 2, 404-419) and involved judging which of two chimeric faces appeared happier, in which the two chimeras were mirror images of each other and each chimera consisted of a smiling half-face joined at the midline to a neutral half-face of the same poser. For the tachistoscopic task, subjects were divided into groups of Fast and Slow responders by a median split of the mean reaction times. For the Fast subjects, judgments were faster in the LVF than in the RVF, and there was a significant interaction between visual field and profile direction, such that responses were faster for medially oriented profiles; i.e., LVF responses were faster for right-facing than for left-facing profiles, with the reverse relationship in the RVF. The Slow responders did not show these effects. Only the Fast group showed the bias for choosing the chimera with the smile on the left as happier, and mean response speed and the LVF advantage on the tachistoscopic test correlated with the leftward bias on the free-vision task for all subjects combined. It was suggested that overall response speed on the face-matching task reflected the extent to which specialized and more efficient right hemisphere functions were activated.     

Number-of-features effects and semantic processing

Participants list many semantic features for some concrete nouns (e.g., lion) and fewer for others (e.g., lime; McRae, de Sa, & Seidenberg, 1997). Pexman, Lupker, and Hino (2002) reported faster lexical decision and naming responses for high number of features (NOF) words than for low-NOF words. In the present research, we investigated the impact of NOF on semantic processing. We observed NOF effects in a self-paced reading task when prior context was not congruent with the target word (Experiment 1) and in a semantic categorization task (concrete vs. abstract; Experiment 2A). When we narrowed our stimuli to include high- and low-NOF words from a single category (birds), we found substantial NOF effects that were modulated by the specificity of the categorization task (Experiments 3A, 3B, and 3C). We argue that these results provide support for distributed representation of word meaning.     

Parallel processing in visual search asymmetry

The difficulty of visual search may depend on assignment of the same visual elements as targets and distractors-search asymmetry. Easy C-in-O searches and difficult O-in-C searches are often associated with parallel and serial search, respectively. Here, the time course of visual search was measured for both tasks with speed-accuracy methods. The time courses of the 2 tasks were similar and independent of display size. New probabilistic parallel and serial search models and sophisticated-guessing variants made predictions about time course and accuracy of visual search. The probabilistic parallel model provided an excellent account of the data, but the serial model did not. Asymptotic search accuracies and display size effects were consistent with a signal-detection analysis, with lower variance encoding of Cs than Os. In the absence of eye movements, asymmetric visual search, long considered an example of serial deployment of covert attention, is qualitatively and quantitatively consistent with parallel search processes.     

Age-of-acquisition effects in semantic processing tasks

In two experiments, we examined whether word age-of-acquisition (AoA) is a reliable predictor of processing times in semantic tasks. In the first task, participants were asked to say the first associate that came to mind when they saw a stimulus word; the second task involved a semantic categorisation between words with a definable meaning and first names. In both tasks, there were significantly faster responses to earlier-acquired than to later-acquired words. On the basis of these results, we argue that age-of-acquisition effects do not originate solely from the speech output system, but from the semantic system as well.     

A left cerebral hemisphere’s superiority in processing spatial-categorical information in a non-verbal semantic format

It has been shown that the left and right cerebral hemispheres (LH and RH) respectively process qualitative or “categorical” spatial relations and metric or “coordinate” spatial relations. However, categorical spatial information could be thought as divided into two types: semantically-coded and visuospatially-coded categorical information. We examined whether a LH’s advantage in processing semantic-categorical information is observed in a non-verbal format, and also whether semantic- and visuospatial-categorical processing are differentially lateralized. We manipulated the colors and positions of the standard traffic light sign as semantic- and visuospatial-categorical information respectively, and tested performance with the divided visual field method. In the semantic-categorical matching task, in which the participants judged if the semantic-categorical information of a successive cue and target was the same, a right visual field advantage was observed, suggesting a LH’s preference for processing semantic-categorical information in a non-verbal format. In the visuospatial-categorical matching task, in which the participants judged if the visuospatial-categorical information of a successive cue and target was identical, a left visual field advantage was obtained. These results suggest that the processing of semantic-categorical information is lateralized in LH, and we discuss the dissociation between the two types of categorical information.     

Automatic and volitional semantic processing in aphasia.

The present study investigated the status of semantic information in aphasia by comparing the performances of aphasic and nonaphasic subjects on two tasks: an automatic semantic facilitation task and a volitional task of relatedness judgment. Both the aphasic and nonaphasic groups evidenced a semantic facilitation effect, in an on-line task of semantic processing. However, those aphasics with severe comprehension and naming disturbances (termed low comprehension aphasics) demonstrated considerable difficulty in judging the relatedness between a pictured object and members of that object's semantic field, the severity of the impairment being greater for those pictures that the low comprehension aphasics were unable to name. The pattern of results can best be explained by supposing the structural integrity of the store of semantic information in aphasia, and in particular in low comprehension aphasia: information that is retrieved and manipulated in judgment-mediated tasks with considerable difficulty.     

Lateralization of object-shape information in semantic processing

An experiment was conducted to examine whether perceptual information, specifically the shape of objects, is activated during semantic processing. Subjects judged whether a target word was related to a prime word. Prime-target pairs that were not associated, but whose referents had similar shapes (e.g. LADDER-RAILROAD) yielded longer "no" responses than unassociated prime-target pairs, suggesting that shape information had been activated. A visual-field manipulation showed that, in right-handed subjects, this effect was localized in the left hemisphere. This finding is consistent with behavioral, brain imaging, and lesion data, which suggest that object shape at the category level is represented in the left hemisphere.     

Locus of control and cerebral asymmetry.

Data about the lack of synchronism of flexor carpi ulnaris peak EMG values of bimanual reactions during a semantic and during a visuospatial discrimination reaction time task are reported. The effects of type of task as well as the presence or absence of an unexpected stimulus preceding the reaction stimulus on lack of synchronism clearly depend upon the locus of control of the subjects, as measured on Rotter's I-E scale. On the basis of several arguments it is proposed that the measure of lack of synchronism reflects in an opposite sense the amount of dopaminergic activation or motor readiness in the sense in which Pribram and McGuinness in 1975 and Tucker and Williamson in 1984 have defined these concepts. The results for 15 women and 18 men show that more internally oriented subjects are more activated by a semantic task and by an unexpected preparatory stimulus in this type of task than more externally oriented subjects. The opposite appears to hold on the visuospatial task and unexpected preparatory stimuli therein. Together with earlier findings about reaction times and a number of relevant findings in the literature, the results are interpreted as indicative of basic differences in asymmetric tonic activation of the cerebral hemispheres between more internally and more externally oriented subjects. A model is proposed to explain phasic activating effects which ensue when tonically more left- or right-activated subjects perform left- or right-hemisphere tasks and when supplementary irrelevant stimuli are received.     

A connectivity model for semantic processing

Summary A connectivity model for semantic processing, based on two major assumptions, is proposed and tested. The representation assumption states that semantically related features are represented by an interconnected structure of features. A network is termed interconnected if each node is linked to at least two other nodes. According to the processing assumption, indirect activation becomes increasingly effective as the number of interconnected nodes increases. The connectivity model thus predicts that more complex concepts will be processed faster than less complex concepts. Experiment 1 was performed to determine the number of features for a set of 72 words and to show that subordinate concepts share common features with their natural superordinate concept. In Experiments 2 and 3 subjects had to judge whether or not a word belonged to a previously defined natural superordinate concept. The results confirm the connectivity model and show that concepts with many features can be classified faster than concepts with only a few features.This research was supported by a Grant of the Max Kade Foundation     

Convergent cortical representation of semantic processing in bilinguals

This study examined whether semantic processes in two languages (English and Spanish) are mediated by a common neural system in fluent bilinguals who acquired their second language years after acquiring their first language. Functional magnetic resonance imaging was performed while bilingual participants made semantic and nonsemantic decisions about words in Spanish and English. There was greater activation for semantic relative to nonsemantic decisions in left and right frontal regions, with greater left frontal activation. The locations of activations were similar for both languages, and no differences were found when semantic decisions for English and Spanish words were compared directly. These results demonstrate a shared frontal lobe system for semantic analysis of the languages and are consistent with cognitive research on bilingualism indicating that the two languages of a bilingual person access a common semantic system.     

Differential thermometer for studying cerebral asymmetry

A device for measuring differences in temperature between the two sides of the head is described. The unit can be used for studying individual differences in cerebral asymmetry.     

Psychopathy, aggression, and the processing of emotional stimuli in non-referred girls and boys

Research shows that individuals with psychopathic traits differ in how they process negative emotional stimuli. However, it is unclear whether these differences are specific to certain types of negative emotional stimulus and whether they are more strongly associated with psychopathic traits or aggression. Further, it is not clear whether or not deficits in emotional processing generalize to females and ethnic minority individuals with psychopathic traits. In this study, we examined the emotional processing of visual stimuli using a dot-probe task in 50 non-referred girls and boys (mean age of 9.30; SD = 2.00). Overall, there was a significant association between proactive aggression and reduced responsiveness to distressing stimuli. In addition, the predicted association between psychopathic traits and reduced responsiveness to distressing stimuli was only found for children high on aggression. Also, the associations among aggression, psychopathic traits, and responsiveness to distressing stimuli did not differ for boys and girls.     

Strategies of semantic categorization in the cerebral hemispheres

Strategies of semantic categorization in intact cerebral hemispheres were studied in two experiments by presenting names of typical and atypical category instances to the left visual field (LVF) (right hemisphere) or to the right visual field (RVF) (left hemisphere). The results revealed that the typicality of instances had a large effect on categorization times in the LVF in both experiments, suggesting that the right hemisphere relies strongly on a holistic, similarity-based comparison strategy. In Experiment 1, the typicality effect was weaker in the RVF than in the LVF. In Experiment 2, a typicality effect in the RVF was observed for the "four-footed animal" category but not for the "bird" category. The hypothesis that the left hemisphere employs a strategy based on defining or necessary features is not supported by the observed typicality effect in the "four-footed animal" category. Instead, it is suggested that the left hemisphere may be able to categorize on the basis of prestored instance-category knowledge. When such knowledge is not available (e.g., as for four-footed animals), a similarity-based comparison strategy is employed by the left hemisphere.     

Developmental changes in the semantic processing of pictures and words

Second- and fifth-graders' semantic decision times for pictures and words were analyzed relative to the predictions derived from unitary- and dual-memory models. At both grade levels, word-word response latencies were greater than picture-word latencies which, in turn, were greater than picture-picture latencies. An interaction between Grade and Condition indicated that verbal access times decreased more than pictorial access times. The data fit the predictions of a memory model postulating category storage in a single memory system as opposed to simultaneous representation in verbal and nonverbal memory systems. It was concluded that with increasing experience verbal access to this single semantic system is more rapid.     

Psychopathy and Responsibility

Some philosophers have argued that the psychopath serves as the ultimate test of the limits of moral responsibility. They hold that the psychopath lacks a deep knowledge of right and wrong, and that Kant's ethics arguably offers the most plausible account of this moral knowledge. On this view, the psychopath's lack of moral understanding is due to a cognitive failure involving practical reason. I argue that the deep knowledge of right and wrong consists of emotional and volitional components in addition to a cognitive one. Hence it is mistaken to claim that the psychopath's moral deficiency is due solely to a cognitive failure, or that his lack of the deep knowledge of right and wrong can be explained entirely in terms of a defect of practical reason. I refer to empirical research to show that the Kantian model of practical reason does not provide a satisfactory account of responsibility of the psychopath in particular or of moral agents in general. On the basis of both philosophical and empirical considerations, I argue that the psychopath is at least partly responsible for his behaviour.     

Parafoveal semantic processing of emotional visual scenes

The authors investigated whether emotional pictorial stimuli are especially likely to be processed in parafoveal vision. Pairs of emotional and neutral visual scenes were presented parafoveally (2.1 degrees or 2.5 degrees of visual angle from a central fixation point) for 150-3,000 ms, followed by an immediate recognition test (500-ms delay). Results indicated that (a) the first fixation was more likely to be placed onto the emotional than the neutral scene; (b) recognition sensitivity (A') was generally higher for the emotional than for the neutral scene when the scenes were paired, but there were no differences when presented individually; and (c) the superior sensitivity for emotional scenes survived changes in size, color, and spatial orientation, but not in meaning. The data suggest that semantic analysis of emotional scenes can begin in parafoveal vision in advance of foveal fixation.     

Electrophysiological evidence of automatic early semantic processing

This study investigates the automatic-controlled nature of early semantic processing by means of the Recognition Potential (RP), an event-related potential response that reflects lexical selection processes. For this purpose tasks differing in their processing requirements were used. Half of the participants performed a physical task involving a lower-upper case discrimination judgement (shallow processing requirements), whereas the other half carried out a semantic task, consisting in detecting animal names (deep processing requirements). Stimuli were identical in the two tasks. Reaction time measures revealed that the physical task was easier to perform than the semantic task. However, RP effects elicited by the physical and semantic tasks did not differ in either latency, amplitude, or topographic distribution. Thus, the results from the present study suggest that early semantic processing is automatically triggered whenever a linguistic stimulus enters the language processor.