Range Of Individual Differences Research Articles

Linking novelty seeking and harm avoidance personality traits to cerebellar volumes

Personality traits are multidimensional traits comprising cognitive, emotional, and behavioral characteristics, and a wide array of cerebral structures mediate individual variability. Differences in personality traits covary with brain morphometry in specific brain regions, and neuroimaging studies showed structural or functional abnormalities of cerebellum in subjects with personality disorders, suggesting a cerebellar role in affective processing and an effect on personality characteristics. To test the hypothesis that cerebellar [white matter (WM) and cortex] volumes are correlated with scores obtained in the four temperamental scales of the Temperament and Character Inventory (TCI) by Cloninger, a total of 125 healthy participants aged 18-67 years of both genders (males = 52) completed the TCI and underwent magnetic resonance imaging. The scores obtained in each temperamental scale were associated with the volumes of cerebellar WM and cortex of right and left hemispheres separately by using linear regression analyses. In line with our hypothesis, novelty seeking (NS) scores were positively associated with WM and cortex cerebellar volumes. Harm avoidance (HA) scores were negatively associated with WM and cortex cerebellar volumes. The range of individual differences in NS and HA scores reflects the range of variances of cerebellar volumes. The present data indicating a cerebellar substrate for some personality traits extend the relationship between personality and brain areas to a structure up to now thought to be involved mainly in motor and cognitive functions, much less in emotional processes and even less in personality individual differences.

Tailoring dietary approaches for weight loss.

Although the ‘Low-Fat' diet was the predominant public health recommendation for weight loss and weight control for the past several decades, the obesity epidemic continued to grow during this time period. An alternative ‘low-carbohydrate' (Low-Carb) approach, although originally dismissed and even vilified, was comparatively tested in a series of studies over the past decade, and has been found in general to be as effective, if not more, as the Low-Fat approach for weight loss and for several related metabolic health measures. From a glass half full perspective, this suggests that there is more than one choice for a dietary approach to lose weight, and that Low-Fat and Low-Carb diets may be equally effective. From a glass half empty perspective, the average amount of weight lost on either of these two dietary approaches under the conditions studied, particularly when followed beyond 1 year, has been modest at best and negligible at worst, suggesting that the two approaches may be equally ineffective. One could resign themselves at this point to focusing on calories and energy intake restriction, regardless of macronutrient distributions. However, before throwing out the half-glass of water, it is worthwhile to consider that focusing on average results may mask important subgroup successes and failures. In all weight-loss studies, without exception, the range of individual differences in weight change within any particular diet groups is orders of magnitude greater than the average group differences between diet groups. Several studies have now reported that adults with greater insulin resistance are more successful with weight loss on a lower-carbohydrate diet compared with a lower-fat diet, whereas adults with greater insulin sensitivity are equally or more successful with weight loss on a lower-fat diet compared with a lower-carbohydrate diet. Other preliminary findings suggest that there may be some promise with matching individuals with certain genotypes to one type of diet over another for increasing weight-loss success. Future research to address the macronutrient intake component of the obesity epidemic should build on these recent insights and be directed toward effectively classifying individuals who can be differentially matched to alternate types of weight-loss diets that maximize weight-loss and weight-control success.

Does Personality Predict Driving Performance in Middle and Older Age? An Evidence-Based Literature Review

Objective: To conduct a literature review of the relationship between personality and driving performance among middle-aged and older adults. Methods: We searched for relevant literature using Web of Science, PsycInfo, and PubMed and consulted with experts for recently published literature not yet catalogued in those databases. Using the American Academy of Neurology's classification criteria, we extracted data from 13 studies and assigned a class (I–IV) to each study. We grouped primary studies into 3 main categories of driving assessment (behavioral assessment: comprehensive driving evaluations, alternative on-road driving evaluations, driving simulations; automobile crashes: state-recorded crashes, self-reported crashes; self-report measures: self-reported driving behaviors). In all, we synthesized the relationship between personality and driving performance for middle-aged and older adults. Results: To assist clinicians and researchers in future considerations of the relationship between personality and driving performance, we provide specific evidence-based recommendations for several driving assessments: on-road driving evaluations (Level B), driving simulations (Level U), state-recorded crashes (Level C), self-reported crashes (Level C), and self-reported driving behaviors (Level C). Conclusions: Overall, we found evidence for personality as a reliable predictor of driving performance among older drivers. However, 2 caveats qualify our conclusions: the research considered only a limited number of personality variables and largely consisted of less valid tests of driving performance. Therefore, to truly understand the relationship between personality and driving performance, future research must consider a wider range of individual differences and employ more stringent tests and methodological designs to measure driving performance.

Adrenocorticotropic tumor cells transplanted into mouse embryos affect pancreatic histogenesis

A wide range of individual differences exist in the total number of functional and structural units in each organ, such as β cells in pancreatic islands, and these units are the basis of the organ's overall function, including its functional reserve. The endocrine environment may influence organ histogenesis, during which functional and structural units are formed and increase in number. We analyzed the effects of a continuous high level of adrenocorticotropic hormone (ACTH) and/or secondarily induced glucocorticoid on histogenesis of the pancreas in mouse embryos. Pituitary tumor-derived AtT20 cells, which secrete ACTH continuously, were injected subcutaneously into mouse embryos at embryonic day (E) 12.5, and the embryos were allowed to develop exo utero until E18.5 (AtT20 group). E18.5 AtT20 group embryos with high ACTH levels (23.74 ± 6.19 ng/mL vs control group, 0.48 ± 0.40 ng/mL, P < 0.05) were examined for the effects on histogenesis of the pancreas. Using serial sections of the E18.5 pancreas, we stereologically measured the volumes, and counted total cell numbers and numbers of mitotic or pyknotic cells of the whole pancreas, endocrine and exocrine cells, and glucagon-immunopositive α cells and insulin-immunopositive β cells in the endocrine part. Although the volumes of the whole pancreas and exocrine part did not change significantly, in the AtT20 group the endocrine part was significantly larger, with fewer pyknotic cells and lower ratios of α and β cells than in the control group. These results suggest that the high level of ACTH and/or glucocorticoid affects histogenesis of the pancreas.

Weighting Function-Based Mapping of Descriptors to Frequency-Gain Curves in Listeners With Hearing Loss

The frequency-gain curve (FGC) is among the most important parameters to consider when fitting a hearing aid. In practice, a prescriptive FGC, derived from the audiogram, is initially applied. In the subsequent fine-tuning stage, the patient often communicates their concerns about the sound quality using descriptors (e.g., "it sounds hollow") and the clinician modifies the FGC accordingly. In this study, we present and evaluate a method that could enhance this process by rapidly mapping descriptors to FGC shapes. In addition, we begin to use this method to examine the extent to which there is across-individual agreement in how descriptors map to FGC shapes. Ten listeners with hearing loss rated the extent to which each of a series of FGCs captured the meaning of a particular descriptor. Regression analyses were conducted to determine the degree to which these ratings were correlated with the gain values associated with each of 25 frequency bands. The array of slopes of these regression lines across frequency bands is termed the weighting function and was interpreted as the FGC shape that corresponded to the descriptor. We used this procedure to determine the FGC shapes associated with four of the most common descriptors used to describe hearing aid sound quality problems ("tinny," "sharp," "hollow," and "in a barrel, tunnel, or well"). The weighting function shape was highly replicable despite variable listener responses, reached asymptotic performance quickly (<20 ratings), and was predictive of listener responses. On the global level, there was some agreement across individuals about how common descriptors mapped to weighting function shape. However, considerable differences were apparent between individuals in terms of the specifics of that mapping. The current approach for descriptor-to-FGC mapping is a quick, reliable method for determining individualized changes to the FGC. Given the range of individual differences in the specifics of the descriptor-to-FGC mappings observed, this approach could be useful in a clinical setting to easily quantify these acoustic parameters. Implementation of such procedures could lead to more personalized fine-tuning of amplification devices.

Learning Styles: Humpty Dumpty revisited

What is a learning style? No one seems to know for sure. The language used by learning style theorists is filled with ambiguities. Price (2004) maintains that “learning style is often used as a metaphor for considering the range of individual differences in learning” (p. 681). Is learning style merely a fanciful metaphor or is it the wave of the future? The research offers mixed results. “Effects on improved test scores with testing conditions matched to student style have been published, but,” Curry (1990) adds, “there are also studies showing no discernible effect attributable to learning style variation” (p. 54). How many distinct learning style models are there? The Coffield (2004) team identified 71 different learning style models, which they subdivided into 13 major and 58 minor models. One of the most popular learning style models comes from Rita and Kenneth Dunn. They have developed an eclectic model featuring 21 (23) different variables that influence a person’s learning style. These variables run all the way from light and temperature to whether the person is analytic or global in his or her thinking. Rita Dunn says about the movement: “I want to convert the world” (Kortland, 2007, p. 8). And well she may. The Dunns’ model is used in the United States, Canada, Great Britain, Australia, and a number of other countries. Is learning style a panacea or a placebo? The jury is still out on that question.

Research on Children with Developmental Coordination Disorder—Some Challenges! Commentary on C. L. Tsai and S. K. Wu (2008)

This commentary focuses on the need for proper inclusion criteria for research on children who have motor problems. Researchers must be aware of the large range of individual differences found in samples used in research on children with Developmental Coordination Disorder. New theoretical perspectives in development and learning are a basis for research and practice.

Prior Heat Stress

The impact of prior heat stress on subsequent aerobic exercise-heat performance has not been studied. To determine whether prior heat stress degrades subsequent aerobic exercise performance in the heat. Eighteen nonheat acclimated males were trained (four practice trials) on an aerobic exercise performance test in 22 degrees C and then divided into two (n = 8) groups. One group (EUHPH; (.)VO2peak = 44 +/- 7 mL x kg x min(-1)) was tested after 90 min of recovery (in 22 degrees C) from 3 h of intermittent light-intensity (<30% (.)VO2peak) exercise-heat (50 degrees C) stress, where sweat losses were matched with fluid intake (3.5 +/- 0.5 L) to maintain euhydration. The other group (EUH; (.)VO2peak = 45 +/- 5 mL x kg x min(-1)) was tested while euhydrated without prior exercise-heat stress. Aerobic performance was determined from a 30-min cycling preload (50% (.)VO2peak) followed by a 15-min time trial in 40 degrees C. Total work during the 15-min performance time trial in EUH and EUHPH was compared, as were the percent changes from the best practice trials. Volunteers were euhydrated (plasma osmolality < 290 mOsm x kg(-1)) and normothermic before each exercise-heat trial. Heart rate and core temperature were not different (P > 0.05) between groups at any time point during exercise. Total work was not different (P > 0.05) at baseline or between EUH (150.5 +/- 28.3 kJ; 2.0 +/- 0.3 kJ x kg(-1)) and EUHPH (160.3 +/- 24.0 kJ; 1.8 +/- 0.2 kJ x kg(-1)). The percent change in total work relative to baseline was not different (P > 0.05) between EUH (-18.7% +/- 9.2%) and EUHPH (-15.0% +/- 7.8%). If hydration and body temperatures recover, prior exercise-heat stress does not result in a greater degradation in aerobic time trial performance in the heat compared with heat exposure alone.

Temperamento em bubalinos: testes de mensuração

O objetivo neste trabalho foi avaliar a aplicabilidade, para búfalos (Bubalus bubalis), de testes de avaliação de temperamento, utilizados para bovinos. Foram avaliados os testes de docilidade, teste de reação a objetos novos, de tronco e de isolamento social em 12 bezerros e suas 12 mães, separadamente. Tanto os bezerros como suas mães responderam a todos os testes com vários comportamentos. Para os bezerros e as mães, os testes que promoveram maior número de comportamentos foram o de tronco e de reação a objetos novos. Houve diferenças individuais (coeficiente de variação de 32-51%) nos resultados de todos os testes tanto nos bezerros como nas mães. Os resultados individuais, em testes de isolamento social e de reação a objetos novos apresentaram correlação positiva tanto com as mães (rs = 0,76, P&lt; 0,01) quanto com os bezerros (rs = 0,66, P&lt; 0,01). Baseados em sensibilidade, relevância e aplicabilidade, o teste de isolamento social e o teste de tronco podem ser sugeridos para avaliarem o temperamento de bubalinos.

Training listeners to identify the sounds of speech: I. A review of past studies.

In this first section of a two-part article we offer an overview of research on listeners' abilities to learn to hear the spectral-temporal details of simple and complex sounds, both speech and non-speech. In the second article, to appear in the October issue of The Hearing Journal, we will describe a new training system based on that science that has recently completed clinical validation trials with users of hearing aids and of cochlear implants.1,2

Neurobiological bases of predisposition to the development of opiate addiction

The range of individual differences in sensitivity to the pharmacological effects of psychoactive substances, especially opiates, is large. Understanding of the processes that control individual differences in the development of opiate addiction is very important for the identification of risk factors and development of effective prophylactics and therapeutic programs. We review the neurobiological bases of the predisposition to the development of opiate addiction. We also focus on the perspectives of studies of the role of the brain nitrergic system in the individual sensitivity to development of opiate addiction.

The Morphology and Syntax of Individuals who use AAC: Research Review and Implications for Effective Practice

A research review of 31 studies pertaining to the morphology and syntax of individuals who use augmentative and alternative communication (AAC) and who had severe speech and physical impairments (SSPI) was completed. Results suggest that, although many individuals who use AAC exhibit comprehension and expression of a wide range of grammatical structures, these individuals are at risk for experiencing grammar deficits. A wide range of individual differences was noted, both within and across many of the investigations. One of the more robust findings was that individuals tended to produce shorter utterances when they used graphic symbol-based AAC systems than would be expected, based on participant profiles; however, there appeared to be a developmental trend toward using longer utterances. There has been a dearth of research pertaining to the development and evaluation of appropriate assessment tools and intervention techniques to enhance grammar acquisition for individuals who use AAC. Considerations for developing such tools and techniques are discussed.

Predicting the ability to learn complex auditory tasks

The goal was to determine whether the ability to learn complex auditory discrimination and identification tasks could be predicted from performance on a screening test battery. The screening battery included auditory tasks chosen on the basis of earlier factor‐analytic studies of individual differences [Kidd et al. JASA 122, 418–435 (2007)], visual acuity tasks, and a test of working memory. These tests were administered to 1,000 college students with normal audiograms. Based on screening test performance, 25 exceptional performers and 25 average performers were selected for prolonged training on three new auditory tasks. The training tasks included multi‐tone pattern discrimination, identification of a vocabulary of sequences of three‐tone syllables, and binary categorization of multi‐dimensional profile‐like stimuli. A broad range of individual differences in post‐training performance was observed on each of these tasks, but differences were not well predicted by screening task performance or estimated general intelligence. Analysis of the screening task performance supported the previously reported independence of individual differences in spectral‐temporal acuity and the recognition of familiar sounds (both speech and nonspeech). Intellectual abilities and visual processing abilities were also independent of each other and of auditory abilities. [Work supported by Grant No. N000140310644 from the Office of Naval Research.]

Individual susceptibility to noise‐induced hearing loss: A review

After 40+ years of study, we can conclude that there is a great range of individual differences in susceptibility to noise‐induced hearing loss (NIHL). The presentation will review and evaluate the major sources of variances: acoustic, where all exposures are evaluated with dBA and some energy‐related metric; exogenous, where the effects of noise can be mitigated by external factors such as temperature, coexposure to chemicals, smoking, etc.; endogenous, where the effects of noise are partially related to an individual’s sex, skin color, acoustic reflex, distortion product suppression, degree of fatigue, and genetic factors.

Retention of Adaptive Control Over Varying Intervals: Prevention of Slip- Induced Backward Balance Loss During Gait

Stability improvements made in a single acquisition session with merely five slips in walking are sufficient to prevent backward balance loss (BLOB) at the end of session, but not after 12 mo. The purpose of this study was to determine whether the effect of an enhanced single acquisition session would be retainable if tested sooner, at intervals of < or =4 mo. Twenty-four young subjects were exposed to blocks of slip, nonslip, and both types of trials during walking at their preferred speed in the acquisition session. In each of the four follow-up sessions around 1 wk, 2 wk, 1 mo, and 4 mo later, these same subjects experienced only a single slip after eight to 13 unperturbed walking trials in an otherwise identical setup. Gait stability was obtained as the shortest distance between the measured center of mass (COM) state (position and velocity) and the mathematically predicted threshold for BLOB at pre- and postslip, corresponding to the instants of touchdown of the slipping limb and liftoff of the contralateral limb, respectively. During the acquisition session, pre- and postslip stability improved significantly, resulting in a reduction of BLOB from 100% in the first slip (S1) to 0% in the last slip (S24), with improvements converging to a steady state, that enabled all of the subjects to avoid BLOB, regardless of whether a slip occurred. During retest sessions, subjects' preslip stability was not different from that in S24, but was greater than that in S1. Their postslip stability was also greater than that in S1 but less than that in S24, resulting in BLOB at a 40% level. No difference was found in any of these aspects between each follow-up session. These adaptive changes were associated with a range of individual differences, varying from no detectable deterioration in all aspects (n = 8) to a consistent BLOB in all follow-ups (n = 3). Our findings demonstrated the extent of plasticity of the CNS, characterized by rapid acquisition of a stable COM state under unpredictable slip conditions and retention of such improvements for months, resulting in a reduced occurrence of unintended backward falling.

Personality and personality disorders: introduction to the special issue

The study of extreme variants of phenomena has always been a challenge for science. While the science of personality has roots in several traditions, historically numerous personality theories and constructs for the assessment and explanation of individual differences have strongly been influenced by the progress made in conceptualizing extreme states of psychological functioning. Yet, division of labour resulted in psychiatry and clinical psychology focusing on deviant or maladaptive and personality psychology specializing on the normal range of individual differences. This special issue of the European Journal of Personality is driven by the idea that linking the study of personality and psychopathology offers insights that neither discipline can achieve on its own. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Evaluation of body composition: a comparison between two systems of bioelectrical impedance

This study compared resistance (R) and body composition obtained via the bioelectrical impedance analysis (BIA) leg‐to‐leg system with the arm‐to‐leg system, using underwater weighing as a standard method. The study subjects were 48 healthy men between 20‐40 years old. No difference was observed in the means of R, per cent body fat (%BF) and fat‐free mass (FFM) obtained from the two systems, but the range of individual differences was from – 70 to + 60ohms for R, from – 5 to + 7kg for FFM and – 8 to + 8 for %BF. The two systems of BIA overestimated the %BF and underestimated FFM. Concludes that LLS is an alternative to assessment of body composition in epidemiological studies. However, independent of the system, BIA is not appropriate for estimating body composition at an individual level.

Preferential Treatment in Television Interviewing: Evidence from Nonverbal Behavior

Implicit and explicit norms in broadcasting require that interviewees be treated in a fair and objective manner and given an equal chance to express themselves, regardless of interviewers' personal liking or preference. Nonverbal behavior of seven Israeli televison interviewers was investigated to discover whether they treated politicians from opposing camps and other interviewees in a differential or fair manner. Very brief clips (averaging 7 seconds) showing the interviewer alone were judged by American students who had no comprehension of speech content. In Study 1, all six interviewers were found to demonstrate differential nonverbal behavior toward interviewees, and four of them treated Labor versus Likud camp politicians in a differential manner. A range of individual differences in effect magnitudes of the differential behavior effects was found. Study 2 focused on two lengthy parallel interviews conducted by a prominent interviewer during the 1996 election campaign with the two candidates for prime minister. The interviewer's nonverbal behavior was found to be blatantly preferential in favor of one candidate. Study 3 examined micro behaviors contributing to the formation of global negative/positive impressions. Correlational analyses yielded several global (presumably universal) mediators: smiling, rhythmical beating hand movements, leaning forward, sarcasm, and attempts to regulate the interviewee. Each interviewer was found to demonstrate a unique personal style in which different nonverbal behaviors mediated the overall impression. The tentative conclusion is that more dominant and aggressive interviewers show more differential/preferential behavior. Social and ethical implications, as well as implications for nonverbal research, are discussed.

Bereavement: theoretical perspectives and adaptation: Canberra, Australia.

This article presents an integrative model for understanding the range of individual differences arising from the bereavement process which occurs through the loss of a significant person, such as a spouse, parent or child. It is suggested that cognitive behavioral models are useful in determining stress reactions to bereavement; however, such models have certain limitations for adaptation purposes. Finally, to enhance well-being, reactions to loss are examined from a clinical perspective by using a five-phase model which outlines holistic adaptation processes, intervention strategies, and time span indicators.

Body-composition measurement in 9–11-y-old children by dual-energy X-ray absorptiometry, skinfold-thickness measurements, and bioimpedance analysis

We compared, in 9-11-y-old children (n=43), three measures of body composition: dual-energy X-ray absorptiometry (DXA), skinfold thickness, and bioimpedance analysis (BIA). The intraclass correlation coefficient (ICC), Bland-Altman procedure, and Spearman rank correlation were used to determine test-retest reliabilities of the three methods and to compare methods. For DXA measurements, the rank correlation between fat-free soft tissue and fat-free mass (FFM) was > 0.99, indicating that bone mineral content did not provide independent information. Thus, subsequent analyses used the two-compartment model (ie, fat mass and FFM) for all three techniques, focusing especially on values for percentage of fat. The test-retest reliabilities for all methods were high (ICCs > 0.994 and no significant differences between trials 1 and 2). The range of individual differences from trial 1 to trial 2 and Bland-Altman limits of agreement suggested that the reliability was greatest for DXA, followed by BIA and skinfold-thickness measurement. The percentage of fat values for the three methods were highly intercorrelated (all Spearman r values > 0.83). However, there was a systematic tendency (P < 0.01) for DXA values (mean: 23.98) to be higher than those derived from skinfold-thickness measurements (mean: 21.05) and BIA (mean: 21.52). The variance in percentage of fat values for BIA was significantly smaller than that for the other two techniques. These findings, along with rather large limits of agreement derived from the Bland-Altman procedure, suggest that the methods should not be used interchangeably.