Lateralized spatial processes and their lexical implications

Two-point discrimination assessment of the upper extremities of healthy young Turkish individuals

Objectives

This study aims to measure the two-point discrimination (TPD) values of the upper extremities of healthy young Turkish individuals.

Patients and methods

Between March 2016 and June 2016, a total of 60 healthy students (31 males, 29 females; mean age: 22.0±1.7 years; range, 19 to 27 years) were included. Eleven grand upper limb parts which take innervation from the brachial plexus were measured with an esthesiometer.

Results

The values at the dominant sides were statistically significantly greater than the non-dominant sides at those areas: upper lateral arm (p=0.001), lower lateral arm (p=0.001), mid-posterior arm (p=0.001), mid-lateral forearm (p=0.001), mid-posterior forearm (p=0.012), skin over the first dorsal interossei muscle (p=0.031), and palmar surface of distal phalanx of the thumb (p=0.045). Both dominant and non-dominant lower lateral arm TPD measurement results increased in males compared to females, indicating a statistically significant difference (p=0.005 and p=0.011, respectively). Also, dominant and non-dominant mid-posterior arm measurement scores were found to statistically significantly increase in males compared to females (p=0.019 and p=0.040, respectively).

Conclusion

Our study results show that laterality, with lower values on the non-dominant side, but not the sex, has an effect on TPD. The findings of this study may be useful in establishing the normative data for TPD in the upper extremity parts of healthy young Turkish individuals.

Two-point discrimination assessment of the lower extremities of healthy young Turkish individuals

OBJECTIVES

To investigate the normative two-point discrimination (TPD) values of the lower extremities of healthy young Turkish individuals.

PATIENTS AND METHODS

Fifty-five healthy, young adults were recruited in this prospective study. Ten lower extremity parts were tested with esthesiometer: proximal thigh, midlateral thigh, midmedial thigh, midposterior thigh, proximal lateral leg, distal lateral leg, medial leg, the tip of great toe, skin over 1-2 metatarsal interspace, skin over 5th metatars at both dominant and non-dominant sides.

RESULTS

There were 27 (49.1%) female and 28 (50.9%) male participants with a mean age of 22.06 ± 1.76 years. The reference values of the TPD of the lower extremities were between 42.4 ± 5.4 mm and 4.0 ± 1.3 mm by females and between 42.6 ± 6.4 mm and 4.4 ± 2.4 mm by males. Test values in the combined group of men and women were statistically greater at the dominant sides than the non-dominant sides at the following areas: proximal lateral leg (p = 0.01), distal lateral leg (p = 0.046), medial leg (p = 0.001), tip of great toe (p = 0.02), skin over 1-2 metatarsal interspace (p = 0.010), skin over 5th metatars (p = 0.002). There was no statistical difference in the test scores of men and women in any of the measured areas, with additional evaluation of both the dominant and the non-dominant sides (p > 0.05).

CONCLUSION

The results of the present study demonstrated that TPD ability varied in different skin areas within the same individual. We found that laterality, though with lower scores on the non-dominant side in some lower extremity parts, but not the gender had an effect on TPD.

Multiple Resources Questionnaire and Workload Profile: Application of Competing Models to Subjective Workload Measurement

This study examines the abilities of three subjective measures of workload to predict dual task performance. The measures compared are: The Workload Profile (WP), the Multiple Resources Questionnaire (MRQ), and the Global Rating Questionnaire (GRQ). Each of these measures is based on a different theoretical model of cognitive workload. Participants first played three computer games. They were asked to rate the games on subjective workload using all three measurement indices. Subjects were then asked to play pairings of the games simultaneously. Only the MRQ significantly predicted task interference, and it also showed the least variability over participants.

The face is the thing: Faces, not emotions, are responsible for chimeric perceptual asymmetry

We used factor analysis to examine relationships among tasks that have previously shown right hemispheric processing asymmetries. We were interested in whether processing emotion displayed by a face constitutes a distinct perceptual process from processing other facial characteristics. Interest in this topic arose after Boles [ 1991 . Factor analysis and the cerebral hemispheres: Pilot study and parietal functions. Neuropsychologia, 29 ( 1 ), 59 - 91 ] found evidence of a common process underlying face processing and then Boles [ 1992 . Factor analysis and the cerebral hemispheres: Temporal, occipital and frontal functions. Neuropsychologia, 30 ( 11 ), 963 - 988 ] found evidence of a distinct process for the processing of the facial emotion. We used seven tasks that measured both face and non-face perception. Analysis of the asymmetries revealed measures from the five face tasks resulted in a single factor, thus failing to support the hypothesis that emotional face perception would involve a separate process from non-emotional face perception. A second factor revealed a separate process underlying enumeration, and a third factor revealed yet another process underlying line bisection. The results indicate that perceiving facial emotion results in right hemisphere processing, and faces as a whole are responsible for such processing.

Schizotypy and hemispheric asymmetry: Results from two Chapman scales, the O-LIFE questionnaire, and two laterality measures

Schizotypy is a multidimensional personality construct representing the extension of psychosis-like traits into the general population. Schizotypy has been associated with attenuated expressions of many of the same neuropsychological abnormalities as schizophrenia, including atypical pattern of functional hemispheric asymmetry. Unfortunately the previous literature on links between schizotypy and hemispheric asymmetry is inconsistent, with some research indicating that elevated schizotypy is associated with relative right over left hemisphere shifts, left over right hemisphere shifts, bilateral impairments, or with no hemispheric differences at all. This inconsistency may result from different methodologies, scales, and/or sex proportions between studies. In a within-participant design we tested for the four possible links between laterality and schizotypy by comparing the relationship between two common self-report measures of multidimensional schizotypy (the O-LIFE questionnaire, and two Chapman scales, magical ideation and physical anhedonia) and performance in two computerised lateralised hemifield paradigms (lexical decision, chimeric face processing) in 80 men and 79 women. Results for the two scales and two tasks did not unequivocally support any of the four possible links. We discuss the possibilities that a link between schizotypy and laterality (1) exists but is subtle, probably fluctuating, unable to be assessed by traditional methodologies used here; (2) does not exist, or (3) is indirect, mediated by other factors (e.g., stress-responsiveness, handedness, drug use) whose influences need further exploration.

Preschool child and adult lateralisation and performance in emotion and language tasks

A total of 34 undergraduate students from the University of Alabama and 34 preschool children completed measures assessing lateralisation and competency in emotion and language processing in order to examine the developmental time course of the underlying lateralised processes. Results indicate different developmental time courses for lateralisation in dichotic words and chimeric faces tasks, and provide some support for the developmental models of Boles, Barth, and Merrill (2008) concerning the relationship between lateralisation and performance.

Multiple resources and mental workload

OBJECTIVE

The objective is to lay out the rationale for multiple resource theory and the particular 4-D multiple resource model, as well as to show how the model is useful both as a design tool and as a means of predicting multitask workload overload.

BACKGROUND

I describe the discoveries and developments regarding multiple resource theory that have emerged over the past 50 years that contribute to performance and workload prediction.

METHOD

The article presents a history of the multiple resource concept, a computational version of the multiple resource model applied to multitask driving simulation data, and the relation of multiple resources to workload.

RESULTS

Research revealed the importance of the four dimensions in accounting for task interference and the association of resources with brain structure. Multiple resource models yielded high correlations between model predictions and data. Lower correlations also identified the existence of additional resources.

CONCLUSION

The model was shown to be partially relevant to the concept of mental workload, with greatest relevance to performance breakdowns related to dual-task overload. Future challenges are identified.

APPLICATION

The most important application of the multiple resource model is to recommend design changes when conditions of multitask resource overload exist.

Asymmetry and performance: Toward a neurodevelopmental theory

Hemispheric asymmetry implies the existence of developmental influences that affect one hemisphere more than the other. However, those influences are poorly understood. One simple view is that asymmetry may exist because of a relationship between a mental process' degree of lateralization and how well it functions. Data scaling issues have largely prevented such investigations, but it is shown that scaling effects are minimized after correction for ceiling and floor effects. After correction, lateralization-performance correlations are pervasive. However, while some correlations are positive, others are negative, with the direction depending on the underlying lateralized process. Two hypotheses are proposed that can account for these relationships by pointing either to individual differences in maturation of the corpus callosum or to developmental limits encountered at different ages of childhood. Their investigation should contribute toward a neurodevelopmental theory of hemispheric asymmetry.

What dot clusters and bar graphs reveal: subitizing is fast counting and subtraction

In two studies, we found that dot enumeration tasks resulted in shallow-sloped response time (RT) functions for displays of 1-4 dots and steep-sloped functions for displays of 5-8 dots, replicating results implicating subitizing and counting processes for low and high ranges of dots, respectively. Extracting number from a specific type of bar graph within the same numerical range produced a shallow-sloped but scallop-shaped RT function. Factor analysis confirmed two independent subranges for dots, but all bar graph values defined a unitary factor. Significantly, factor scores and asymmetries both showed correlations of bar graph recognition to dot subitizing but not to dot counting, strongly suggesting that subitizing was used in both enumeration of low numbers of dots and bar graph recognition. According to these results, subitizing appears to be a nonverbal process operating flexibly in either additive or subtractive fashion on analog quantities having spatial extent, a conclusion consistent with a fast-counting model of subitizing but not with other models of the subitizing process.

A Large-Sample Study of Sex Differences in Functional Cerebral Lateralization

For practitioners, the importance of sex differences in lateralization lies in their potential prediction of susceptibility to and recovery from hemispheric damage. However, previous literature reviews suggest that sex accounts for only 0.1-1% of the variance in asymmetry scores. Here a large-sample, single-laboratory approach uses tasks requiring the recognition of bargraphs, dichotic words, facial emotions, locations, and visual words, and visual line bisection, each sensitive to lateralization of a separate mental module. The results agree with previous reviews, with sex accounting for a maximum of 0.9% and an average of 0.09% of the variance, suggesting that sex has little predictive clinical utility. However, the strength of relationship between sex and laterality depends on the nature of the lateralized task, presumably because of differences between tasks in underlying lateralized modules.

Predicting dual-task performance with the Multiple Resources Questionnaire (MRQ)

OBJECTIVE

The objective was to assess the validity of the Multiple Resources Questionnaire (MRQ) in predicting dual-task interference.

BACKGROUND

Subjective workload measures such as the Subjective Workload Assessment Technique (SWAT) and NASA Task Load Index are sensitive to single-task parameters and dual-task loads but have not attempted to measure workload in particular mental processes. An alternative is the MRQ.

METHOD

In Experiment 1, participants completed simple laboratory tasks and the MRQ after each. Interference between tasks was then correlated to three different task similarity metrics: profile similarity, based on r(2) between ratings; overlap similarity, based on summed minima; and overall demand, based on summed ratings. Experiment 2 used similar methods but more complex computer-based games.

RESULTS

In Experiment 1 the MRQ moderately predicted interference (r = +.37), with no significant difference between metrics. In Experiment 2 the metric effect was significant, with overlap similarity excelling in predicting interference (r = +.83). Mean ratings showed high diagnosticity in identifying specific mental processing bottlenecks.

CONCLUSION

The MRQ shows considerable promise as a cognitive-process-sensitive workload measure.

APPLICATION

Potential applications of the MRQ include the identification of dual-processing bottlenecks as well as process overloads in single tasks, preparatory to redesign in areas such as air traffic management, advanced flight displays, and medical imaging.

Brain State-dependent Functional Hemispheric Specialization in Men but not in Women

Hemispheric specialization is reliably demonstrated in patients with unilateral lesions or disconnected hemispheres, but is inconsistent in healthy populations. The reason for this paradox is unclear. We propose that functional hemispheric specialization in healthy participants depends upon functional brain states at stimulus arrival (FBS). Brain activity was recorded from 123 surface electrodes while 22 participants (11 women) performed lateralized lexical decisions (left hemisphere processing) on neutral and emotional (right hemisphere processing) words. We determined two classes of stable FBS, one with right anterior-left posterior orientations (RA-LP maps) and one with left anterior-right posterior orientations (LA-RP maps). Results show that functional hemispheric specialization is dependent upon the class of FBS and gender. Of those with LA-RP maps, only men showed a strong emotional word advantage (EWA) after left visual field (right hemisphere) presentation, but no EWA after right visual field (left hemisphere) presentation. Subsequent to all other brain states, there was an almost equal EWA after presentation to either visual field. Only about half of the FBS in men led to the pattern of functional hemispheric specialization. We suggest that 'split-brain' research may be marginally describable by a model, but only in exceptional situations, while in connected brains this functional hemispheric specialization is only one of many dynamic states.