Divided Visual Field Technique Research Articles

Lexical decision performance using the divided visual field technique following training in adults with intellectual disabilities with and without Down syndrome

ABSTRACTStudies of brain lateralization in individuals with non-specific intellectual disability and Down syndrome suggest atypical brain lateralization to speech perception. According to the biological dissociation model, the right hemisphere (RH) mediates speech perception and the left hemisphere (LH) mediates motor control in Down syndrome. The current study aimed to test, for the first time, brain lateralization in both non-specific intellectual disability and Down syndrome, compared to individuals with typical development. Furthermore, bilateral word presentation was utilized to assess interhemispheric communication. Twenty adults with non-specific intellectual disability, 14 adults with Down syndrome, and 30 adults with typical development participated in the study. Participants in the non-specific intellectual disability and Down syndrome groups were trained to perform the task prior to the experiment. The results showed that whereas hemispheric lateralization did not differ between individuals with non-specific intellectual disability and typical development, individuals with DS showed reduced brain lateralization in comparison to adults with typical development. All three groups showed no significant difference between words presented to the LH and bilaterally. Our results also show that individuals with intellectual disabilities can benefit from training programmes and that they may perform equally as fast as their typically developing peers.

The impact of perceptual changes to studied items on ERP correlates of familiarity and recollection is subject to hemispheric asymmetries

It is still unclear which role the right hemisphere (RH) preference for perceptually specific and the left hemisphere (LH) bias towards abstract memory representations play at the level of episodic memory retrieval. When stimulus characteristics hampered the retrieval of abstract memory representations, these hemispheric asymmetries have previously only modulated event-related potential (ERP) correlates of recollection (late positive complex, LPC), but not of familiarity (FN400). In the present experiment, we used stimuli which facilitated the retrieval of abstract memory representations. With the divided visual field technique, new items, identical repetitions and color-modified versions of incidentally studied object pictures were presented in either the right (RVF) or the left visual field (LVF). Participants performed a memory inclusion task, in which they had to categorize both identically repeated and color-modified study items as ‘old’. Only ERP, but not behavioral data showed hemispheric asymmetries: Compared to identical repetitions, FN400 and LPC old/new effects for color-modified items were equivalent with RVF/LH presentation, but reduced with LVF/RH presentation. By promoting the use of abstract stimulus information for memory retrieval, we were thus able to show that hemispheric asymmetries in accessing abstract or specific memory representations can modulate ERP correlates of familiarity as well as recollection processes.

ERP evidence for hemispheric asymmetries in exemplar-specific explicit memory access

The right cerebral hemisphere (RH) appears to be more effective in representing visual objects as distinct exemplars than the left hemisphere (LH) which is presumably biased towards coding objects at the level of abstract prototypes. As of yet, relatively little is known about the role that asymmetries in exemplar-specificity play at the level of explicit memory retrieval. In the present study, we addressed this issue by examining hemispheric asymmetries in the putative event-related potential (ERP) correlates of familiarity (FN400) and recollection (LPC). In an incidental study phase, pictures of familiar objects were presented centrally. At test, participants performed a memory inclusion task on identical repetitions and different exemplars of study items as well as new items which were presented in only one visual hemifield using the divided visual field technique. With respect to familiarity, we observed exemplar-specific FN400 old/new effects that were more pronounced for identical repetitions than different exemplars, irrespective of the hemisphere governing initial stimulus processing. In contrast, LPC old/new effects were subject to some hemispheric asymmetries indicating that exemplar-specific recollection was more extensive in the RH than in the LH. This further corroborates the idea that hemispheric asymmetries should not be generalized but need to be distinguished not only in different domains but also at different levels of processing.

Hemispheric involvement in native and non-native comprehension of conventional metaphors

The present study examined hemispheric processing of conventional metaphors in native (L1) and non-native (L2) language using the divided visual field technique. Participants included 25 native Hebrew speakers and 24 bilinguals who acquired English as L1 and Hebrew as L2. In Experiment 1, the two groups performed a semantic judgment task on conventional metaphors and literal Hebrew word pairs, and in Experiment 2, the processing of the expressions was compared between the two L1s. The results of the two experiments demonstrated a left hemisphere advantage for processing conventional metaphoric expressions in L1, but a right hemisphere advantage for processing the same kind of stimuli in L2. No such L1-L2 difference in hemispheric involvement was observed for literal word pairs. These results support the Fine-Coarse Semantic Coding Theory and the Graded Salience Hypothesis and suggest that the metaphoric meanings of conventional metaphors may appear less salient for a non-native speaker.

Oral Presentations

Introduction: The current study aimed at further tracking the neurophysiological correlates of giftedness. Whereas electrophysiological studies provided evidence for an accelerated cognitive maturation in gifted children, behavioural studies argue for particularities in hemispheric lateralisation. The Event-Related Potentials (ERPs) were recorded in order to investigate hemisphere specialisation in giftedness. Materials and Methods: The ERPs were recorded from 50 right-handed children ranged from 8 to 12 years divided into two age-matched groups: 25 gifted children, and 25 controls. All the children performed a neuropsychological set including the Intellectual Quotient (IQ) assessment. The EEG was recorded from 26 electrodes, while children performed a decision task and a matrix completion task using the divided visual field technique. Results: The ERP analyses showed significant differences in both the N400 and the P300 latency bands during the two tasks arguing for an enhanced right hemisphere involvement. The pattern of ERPs demonstrated particularities in the hemispheric specialisation as a function of the IQ profile. Discussion/conclusion: The present investigation is in line with the cognitive style usually observed in giftedness favouring holistic rather than analytic information processing with higher abilities to perform simultaneous rather than sequential processes. Assessing the cognitive style of gifted children using neurophysiological investigations permits to better understand their pedagogic needs.

Hemispheric Differences in the Processing of Words Learned Early Versus Later in Childhood

ABSTRACT The research investigated whether there are hemispheric differences in processing for words acquired early in childhood (early AoA) and words acquired later in childhood (late AoA). We hypothesized that because of recent evidence suggesting that there is a right hemisphere dominance in early childhood, early AoA words would be represented in the right hemisphere, and late AoA words would be represented in the left hemisphere. This hypothesis differs from an early view that late AoA words would be represented in the left hemisphere, and early AoA words would be represented in both hemispheres (Gazzaniga, 1974). We report two experiments using the divided visual field (DVF) technique. The results showed that there was a right visual field (RVF)/left hemisphere (LH) advantage only for late AoA words. For early AoA words, there was a left visual field (LVF)/right hemisphere advantage (RH). Implications for theories of hemispheric differences in word processing are discussed.

The Lateralizer: a tool for students to explore the divided brain

Despite a profusion of popular misinformation about the left brain and right brain, there are functional differences between the left and right cerebral hemispheres in humans. Evidence from split-brain patients, individuals with unilateral brain damage, and neuroimaging studies suggest that each hemisphere may be specialized for certain cognitive processes. One way to easily explore these hemispheric asymmetries is with the divided visual field technique, where visual stimuli are presented on either the left or right side of the visual field and task performance is compared between these two conditions; any behavioral differences between the left and right visual fields may be interpreted as evidence for functional asymmetries between the left and right cerebral hemispheres. We developed a simple software package that implements the divided visual field technique, called the Lateralizer, and introduced this experimental approach as a problem-based learning module in a lower-division research methods course. Second-year undergraduate students used the Lateralizer to experimentally challenge and explore theories of the differences between the left and right cerebral hemispheres. Measured learning outcomes after active exploration with the Lateralizer, including new knowledge of brain anatomy and connectivity, were on par with those observed in an upper-division lecture course. Moreover, the project added to the students' research skill sets and seemed to foster an appreciation of the link between brain anatomy and function.

Conventionalisation of novel metaphors: A shift in hemispheric asymmetry

According to recent psycholinguistic theory conventional metaphors may be understood via categorisation whereas novel metaphors are understood via comparison processes. Furthermore, behavioural evidence suggests that the process of conventionalising novel metaphors is accompanied by a shift from comparison to categorisation. However, changes in correlative neuropsychological processing as a result of the conventionalisation of novel metaphors have not been tested. Previous studies have provided evidence for special right hemisphere involvement in the comprehension of two-word novel, but not conventional, metaphoric expressions. On the basis of the latter evidence we used the divided visual field technique to test the possibility that the conventionalisation of novel metaphors will be accompanied by a shift from right to left hemisphere processing. The results suggest that repeated exposure to novel metaphoric stimuli changes the pattern of hemispheric asymmetry.

Patterns of brain asymmetry in the perception of positive and negative facial expressions

The divided visual field technique was used to investigate the pattern of brain asymmetry in the perception of positive/approach and negative/withdrawal facial expressions. A total of 80 undergraduate students (65 female, 15 male) were distributed in five experimental groups in order to investigate separately the perception of expressions of happiness, surprise, fear, sadness, and the neutral face. In each trial a target and a distractor expression were presented simultaneously in a computer screen for 150 ms and participants had to determine the side (left or right) on which the target expression was presented. Results indicated that expressions of happiness and fear were identified faster when presented in the left visual field, suggesting an advantage of the right hemisphere in the perception of these expressions. Fewer judgement errors and faster reaction times were also observed for the matching condition in which emotional faces were presented in the left visual field and neutral faces in the right visual field. Other results indicated that positive expressions (happiness and surprise) were perceived faster and more accurately than negative ones (sadness and fear). Main results tend to support the right hemisphere hypothesis, which predicts a better performance of the right hemisphere to perceive emotions, as opposed to the approach–withdrawal hypothesis.

Models of brain asymmetry in emotional processing.

Two models of brain asymmetry in emotional processing were reviewed: the right hemisphere and the valence hypotheses. The first states a dominant role for the right hemisphere in emotional processing, whereas the second assumes that the left hemisphere is dominant for positive emotions and the right hemisphere for negative ones. Different methods, such as the divided visual field technique, have supported both hypotheses. The amygdala and the prefrontal cortex are presented as important structures involved on brain asymmetry in emotional processing. The paper ends pointing out new perspectives for the study of the neural subtrates of different components of emotions.

Rigid And Nonrigid Objects In Canonical And Noncanonical Views: Hemisphere-Specific Effects On Object Identification

We compared the performance in a picture-name matching task of 10 patients suffering from left cerebral hemisphere (LH) damage and 10 from right hemisphere (RH) damage. The tasks showed detailed figures of nonrigid objects (animals) and rigid objects (artefacts), and each object was shown in two separate views: a noncanonical view (an unusual perspective for rigid objects or a contorted pose for the nonrigid ones) and a canonical view (a typical perspective and pose). Patients with LH damage were specifically impaired in identifying noncanonical (contorted) poses of nonrigid objects (animals). In a second picture-name matching experiment, using the divided visual field technique, normal subjects matched names to images of nonrigid shapes (animals) shown in canonical and noncanonical perspectives of noncontorted, typical poses of the animals. It was found that the normal subjects' RH identified these perspectives better than their LH. We conclude that computationally different problems are solved by different cerebral mechanisms when identifying flexible objects and when identifying rigid objects. We propose the idea that identifying flexible objects when their shapes contort relies on accessing stored descriptions of objects' parts and their “categorical” spatial relations and that both types of information are encoded better by the LH. In contrast, we propose that the RH is more adept at identifying different perspectives of rigid objects (and flexible objects when their shapes do not contort) because of this hemisphere's superiority in encoding specific global shapes and their views, and in coordinate spatial transformation.

Form-Specific Visual Priming in the Left and Right Hemispheres

Word fragment completion performance was examined for items that were presented in the same or different letter case at study and test. During the study phase words and nonwords were presented at central fixation, then during the test phase a divided visual field technique was used in which word fragments were presented briefly to the right hemisphere (left visual field) or the left hemisphere (right visual field). Previous research using the word stem completion task indicated that only the right hemisphere was sensitive to case changes in words from study to test. In contrast, the current results indicate that in the fragment completion task the priming effects for the test items presented to either hemisphere were greater when the fragments were in the same compared to different letter case at study and test. These results indicate that both hemispheres are capable of supporting form-specific visual implicit memory.

The Role of Temperament and Gender in Functional Hemispheric Asymmetry and the Perception of Emotion

Research investigating the relation between Functional Hemispheric Asymmetry (FHA) and the perception of affect in clinical as well as normal populations, is characterized by contradictory findings regarding the role of the different hemispheres, especially as regards the perception of various valencies of emotions. Although various methodological problems or error variances are often blamed for the contradictory findings and general lack of consensus, the literature is increasingly pointing to the existence of evidently reliable individual differences between people regarding their hemispheric functioning. The problem investigated in this study was to determine the possible role of some organismic variables in FHA. The objectives of this study were to determine whether there were significant differences in the direction of FHA-differences, as well as the relative performance, of groups divided according to gender and temperament characteristics, and whether the relevant organismic variables offered a possible means of explaining the contradictions in research results on FHA and the perception of emotion. The subject population ( N = 112) comprised four groups of right-handed students selected in terms of gender and temperament (introversion-extraversion). Differential hemispheric performance in terms of response accuracy and latency was determined by means of the Divided Visual Field Technique (DVFT). The results indicated that gender but not the temperament dimension of introversion-extraversion, plays a significant role in the degree and direction of FHA in the perception of emotion. It appears that the organismic variable gender could possibly offer a partial explanation for the contradictory results in the literature specifically with regard to FHA in the perception of emotion generally, and in respect of different valencies of emotion. However, the lack of significance in some of the results, especially with regard to men, impedes a firm empirical conclusion and explanation of the results.

Right Hemisphere Involvement in Processing Later-Learned Languages in Multilinguals

In two experiments, multilingual Papua New Guinean subjects were tested using a divided visual field technique designed to determine hemispheric laterality for English and for Tok Pisin. Various factors including age of acquisition, proficiency, mode of instruction, and number of years that the language had been used were considered in relation to language laterality. Only age of acquisition proved to be a significant contributor to the laterality effects obtained; older acquirers of both English and Tok Pisin showed greater right hemisphere involvement than early acquirers. Although proficiency did not seem to be related to language laterality, it too was systematically affected by acquisition age. Older acquirers of English performed significantly poorer than younger acquirers on all four of the language-usage tests given. The strong influence of acquisition age on cerebral laterality for language and proficiency is interpreted as supporting a critical period for language learning.

Declarative and Nondeclarative Memory: Multiple Brain Systems Supporting Learning and Memory

Abstract The topic of multiple forms of memory is considered from a biological point of view. Fact-and-event (declarative, explicit) memory is contrasted with a collection of non conscious (non-declarative, implicit) memory abilities including skills and habits, priming, and simple conditioning. Recent evidence is reviewed indicating that declarative and non declarative forms of memory have different operating characteristics and depend on separate brain systems. A brain-systems framework for understanding memory phenomena is developed in light of lesion studies involving rats, monkeys, and humans, as well as recent studies with normal humans using the divided visual field technique, event-related potentials, and positron emission tomography (PET).

Functional Hemispheric Asymmetry and Psychological Differentiation

A differentiation model is proposed in which a relationship between neuropsychological (perceptual) differentiation on the one hand, and psychological (personality) differentiation on the other hand is hypothesized. An empirical investigation of the basic hypothesis is reported. The fit of the global model to empirical data is evaluated with the aid of the RAMONA program for path analysis with latent variables. In the advanced model differentiation is assumed to be a formal property of an organismic system. Neuropsychological differentiation is conceptualized in terms of the extent of functional hemispheric asymmetry (FHA), and operationalized in the auditory and visual modalities with the aid of the dichotic stimulation technique (DST) and the divided visual field technique (DVFT). Psychological differentiation is conceptualized in terms of the degree of healthy, optimal personality functioning (OPF), and is operationalized with indices of communicative competency, degree of self-actualization and of personal autonomy. A significant relationship between FHA and OPF was found. This indicates a correspondence between the degree of differentiation in diverse domains of functioning (perceptual and personality-wise), in healthy, normal subjects. In this study phenomena described in different specialization areas of psychology (neuropsychology and personology) are linked in a shall bridge theory for which empirical support has been found. This is a modest step towards interdisciplinary understanding.

Left hemisphere superiority for visuospatial functions in left-handers

Male and female left- and right-handers have been tested with a divided visual field technique on a visuospatial (discrimination of angle width) and on a verbal task (vowel-consonant discrimination) using either a choice or a Go-No-go manual reaction time paradigm. Right-handers showed the expected pattern of hemispheric asymmetries with an advantage of the right hemisphere in the visuospatial task and an advantage of the left hemisphere in the verbal task. Such effects were statistically reliable only in male subjects. Left-handers, on the contrary, showed a different pattern of asymmetries. In the visuospatial task there was an overall superiority of the left hemisphere, while no hemispheric asymmetry was found in the verbal task.

Qualitatively different organizational structures of lexical knowledge in the left and right hemisphere

The present study investigates and discusses the organization of lexical knowledge in the intact left and right hemisphere within the framework of hemisphere-specific cognitive modes of processing. Using a divided visual field technique, word pairs of concrete nouns had to be judged. Semantic relation was either intraconceptual (coordinates) or interconceptual (locative). The results suggest that in the left hemisphere, lexical structures are predominantly based on intraconceptual relationships corresponding to its analytic sequential processing mechanism, whereas in the right hemisphere, lexical entries are exclusively associated by means of interconceptual relationships in accordance with its “gestalthaft” holistic processor.

Visual hemispace differences reflect hemisphere asymmetries

The relationship between the representation of the extracorporeal visual hemispace and the contralateral hemisphere has been investigated by presenting visual stimuli foveally either in the right or in the left hemispace. In a lexical decision task (Exp. 1) and a face-familiarity decision task (Exp. 2) lateral asymmetries very similar to those obtained using the divided visual field technique have been found. These results suggest that under particular circumstances the hemispace representation in the contralateral hemisphere overrides the retinal representation. Finally, it was found that in a lexical decision task performance with stimuli in the right hemispace was very similar to that with stimuli in a central position. The physiological and adaptive meaning of this phenomenon is discussed.

Difference in the Vigilance Performance of the Right and Left Hemispheres

A vigilance task was presented to either the right or left hemisphere alone by means of a divided visual field technique. The left hemisphere was found to be superior in detection and to give rise to fewer false positives. Handedness was found to be related to performance in the right hemisphere group. It is argued that the results suggest the presence of two vigilance systems within the brain, a primary system operating initially at a high level, showing decrement with time, and associated with the left hemisphere, and a secondary system showing no decrement, but operating at a lower level, associated with the right hemisphere.