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The main aim of this study was to explore the etiology of relations between general cognitive ability (g) and different hierarchical phenotypic levels of the Five Factor Model (FFM), including the General Factor of Personality (GFP), the Big Two, the five domains of the FFM, and their 30 facets. The second aim was to detect personality facets that contribute to the prediction of general intelligence. The sample consisted of 424 young adult twins (134 pairs of monozygotic twins) on whom the NEO-PI-R and Advanced Progressive Matrices were administered. The results did not support hierarchical solutions above the FFM. Thus, five-domain and facet level of personality were analyzed, showing that only Openness and Neuroticism had significant genetic or environmental correlations with intelligence. The several facets from all domains had significant associations, among which Ideas and Positive Emotions showed the highest positive correlations, while Order and Modesty showed the highest negative genetic correlations with intelligence. Furthermore, seven facets significantly predicted g factor (35%), with higher genetic (0.52) than environmental (0.13) correlations with intelligence. The results reveal the common genetic basis of narrow traits and intelligence, highlighting the importance of specific traits in the explanation of general cognitive abilities.

The first twin study in Serbia began in 2011 as a part of the research project, ‘Psychological Foundations of Mental Health: Hereditary and Environmental Factors’. At the same time, the research team from the Faculty of Philosophy and Faculty of Medicine in Novi Sad established the first Serbian twin registry. The registry is intended primarily for the purpose of the research in behavioral genetics, as well as potential future studies in human genetics. It includes information on 1658 volunteers, including twin-pairs, their parent and siblings. The behavioral genetic study of adult twins has been focused on the hereditary and environmental sources of variance of different psychological characteristics, such as personality traits, cognitive abilities, executive functions and aggression, as well as some anthropometric measures and aspects of mental and physical health. Certain molecular genetic analyses have also been performed. The research team is currently starting the longitudinal twin study of children, which will be focused on different indicators of emotional, cognitive and physical development.

The first aim of this study was to explore the aetiology of phenotypic relationships between different measures of executive functions. The second objective was to examine sources of the covariation between different measures of executive functions and the measure of general cognitive ability. The study sample consisted of 468 twins (154 pairs of monozygotic twins and 80 pairs of dizygotic twins) of the same and different gender who grew up together. Executive functions were evaluated by the Wisconsin Card Sorting Test, the Trail Making Test – form B, and verbal fluency tests. Raven's Advanced Progressive Matrices were used as a measure of general cognitive ability. The study results suggest a primarily genetic origin of the mutual covariation of different executive measures and their covariation with the general cognitive ability construct. While the shared genetic variance primarily lies in the bases of similarity/unity of the used cognitive measures, their particularity/difference is determined by a specific unshared environment. The obtained result on the presence of a single general genetic factor, which can be singled out in the case of different executive measures, at least partially speaks in favor of the thesis about the unity of various executive measures and the existence of a common basic ability. Together with the specific unshared environment, the specific genetic influence speaks in favor of a difference between each of the individual measures.

Aggressive and impulsive behaviors have shown sufficient genetic influences and high co-occurrence, thus the question is whether dispositions for these behaviors share unique genetic or environmental contributions. The aim of this research was to explore etiology of phenotypic relationships between aggressiveness and impulsiveness. More precisely, we tested which component of aggressiveness (affective, behavioral, or cognitive) shared the most underlying genetic and environmental influences with impulsiveness. There were applied Serbian adaptation of the Buss-Perry Aggression Questionnaire as a measure of three aggressiveness components, and Behavioral Activation System scale from the Revised Sensitivity Theory Questionnaire as a measure of impulsiveness, on a sample of 208 adult twin pairs (132 pairs were monozygotic). Results of a multivariate biometric method showed that the aggressiveness and impulsiveness could be explained by the common additive genetic (6% of impulsiveness and 16- 31% of aggressiveness components), and common non-shared environmental contributions (1% of impulsiveness and 11-47% of aggressiveness components), but those contributions were rather small. An affective component of aggressiveness (anger) showed the most genetic similarity with impulsiveness, indicating that the lack of anger and behavior regulation shared partially the same genetic basis. However, aggressiveness and impulsiveness contained a larger proportion of the specific genetic and environmental effects, which confirmed a distinction between these phenomena.

The need for a research and practical tool, such as a short, reliable, and valid personality assessment test, suggests researchers to create shortened versions of original instruments. Reinforcement sensitivity questionnaire (RSQ) was created in line with some basic premises of revised Reinforcement sensitivity theory, which proposes three motivational and emotional systems: Behavioral inhibition system (BIS), responsible for scanning environment for potential threats, Behavioral activation system (BAS), responsible for aproaching behavior, and the Fight/Flight/Freeze system (FFFS), responsible for behavior in the present threat. RSQ comprises five scales: BIS, BAS, Fight, Flight, and Freeze. The aim of this study was to develop a short version of RSQ, which would be beneficial to both research and practical purposes. Item response theory analyses were used for item selection. The study comprised two samples of participants, whereby Sample 1 (N = 837, 34.6% male, aged 18 - 82, M = 31.63, SD = 13.54) served as the derivation sample, while Sample 2 (818 participants, 43.6% male, 18-75 years, M = 29.65, SD = 12.52) served as validation sample. Factorial validity of the short RSQ was examined on both Sample 1 and Sample 2. Convergent and divergent validity of the short RSQ was examined using RST-PQ, Jackson-5, BIS/BAS scales, and Big Five Inventory. The results point to satisfactory internal consistency, factorial validity, and construct validity of the short RSQ, suggesting that it is an adequate measure for research settings or other contexts which require the use of short personality questionnaires.

Inteligencija i školsko postignuće, kao tesno vezani, ispitivani su zajedno od najranijih empirijskih istraživanja ovih konstrukata. Međutim, tek rezultati bihejvioralno-genetičkih studija pružaju potpunu sliku o faktorima koji utiču na inteligenciju i školski uspeh, specifikujući etiologiju njihovog odnosa. Osnovni cilj ovog istraživanja usmeren je na procenu genetskih i sredinskih faktora koji utiču na kovariranje među merom opšte intelektualne sposobnosti i osnovnoškolskog i srednjoškolskog uspeha. Istraživanje je obuhvatilo 340 parova blizanaca oba pola, od toga 168 monozigotnih i 172 dizigotna blizanca, u starosnoj dobi 18–44 godine. Udeo pojedinih izvora kovariranja između ispitivanih fenotipa testiran je multivarijantnim biometrijskim metodom. Uvid u fenotipske korelacije opšte intelektualne sposobnosti, uspeha u osnovnoj školi i uspeha u srednjoj, ukazuje da je reč o konstruktima koji međusobno umereno koreliraju (.33–.53). Opšti/zajednički genetski uticaj objašnjava najveći deo kovarijanse školskog uspeha (kako u osnovnoj, tako i u srednjoj školi) i opšte intelektualne sposobnosti, što govori u prilog pretpostavci da isti set gena određuje etiologiju individualnih razlika na ispitivanim varijablama. Objašnjenju korelacije između uspeha u osnovnoj i uspeha u srednjoj školi umereno doprinose i mere opšte/zajedničke deljene sredine. Pored nedeljenih sredinskih uticaja, ono što razlikuje ispitivane konstrukte jesu uticaji specifičnih genetskih faktora, koji su jedinstveni za svaki konstrukt.

The paper presents validation of the Reinforcement Sensitivity Questionnaire (RSQ), measuring the constructs of the Revised Reinforcement Sensitivity theory (RST). The research was conducted on a sample of 565 participants, using three measures of the constructs of the Revised Reinforcement Sensitivity Theory – the Behavioral Inhibition System/Behavioral Approach System (BIS/BAS) scale, Reinforcement Sensitivity Theory Personality Questionnaire (RST-PQ), and Reinforcement Sensitivity Questionnaire. The results of confirmatory factor analysis suggest good internal validity of the RSQ, while the results of principal components analysis show that the RSQ scales are significantly related to other RST measures.

The advent of combined antiretroviral therapy (cART) has prolonged the life expectancy of HIV + individuals and decreased the incidence of HIV-associated dementia. However, milder forms of neurocognitive impairment remain common and are often associated with poor daily functioning and lower medication adherence. This paper presents a research aimed at exploring the cognitive status differences between HIV + subjects (N = 39) on cART therapy and a group of demographically comparable healthy subjects (N = 39) in Serbia. The significance of differences between the HIV + group and the healthy control group in performance in six cognitive domains was tested using the multivariate analysis of variance. Results showed a lower performance of the HIV + group in the domains of attention/working memory, and learning. HIV-related clinical variables were not significantly associated with cognitive performance. An older age in HIV + patients was significantly related to a lower performance in all six cognitive domains, as opposed to healthy subjects, implying a synergistic interaction between HIV and aging, resulting in accentuated cognitive difficulties. Our findings suggest that even with the absence of a subjective experience of cognitive deficits and with a good basic control of the illness, a certain degree of cognitive deficit can be observed in the tested group.

The main aim of this study is to estimate the heritability of AFFM and PEN dimensions, including 67 pairs of twins (34 monozygotic and 33 dizygotic) of both genders, aged 18 - 44. The heritability has been estimated by the biometric method, two full (ACE and ADE) and three reduced (AE, DE and CE) models tested for each personality trait. Taking into consideration the AFFM dimensions, additive genetic factors and a non-shared environment contribute the most significantly to the phenotypic variation of activity, sociability and the impulsive sensation seeking; anxiety and aggressiveness are best accounted for by the dominant genetic effects. In the PEN domain, fit indicators suggest that ACE and the reduced AE models provide the best explanation for the phenotypic manifestations of neuroticism, while ACE and CE models account for the variation of L scale. Although the fit indicators calculated for extraversion and psychotic behavior are somewhat problematic, the parameter estimates show that extraversion is best accounted for by the additive genetic variance, shared environmental effects, and the non-shared environment, whereas psychotic behavior is the most adequately explained by both shared and non-shared environmental effects.

U nameri da se na sveobuhvatan način ispitaju ponašanja karakteristična za nasilnu interakciju među učenicima osnovnih i srednjih škola, konstruisan je Upitnik za procenu vršnjačkog nasilja (PRONA). Upitnik sadrži 20 stavki kojima su obuhvaćene dve skale između kojih postoji visoka kongruencija na uzorku učenika osnovnih i srednjih škola. Jedna skala se odnosi na procenu trpljenja nasilja (Izloženost vršnjačkom nasilju), a druga na činjenje nasilja (Sklonost ka nasilnom ponašanju). Sadržaj stavki obuhvata indikatore lakših i težih oblika fizičkog nasilja, kao i psihološkog, odnosno emocionalnog nasilja. Skale imaju zadovoljavajuće metrijske karakteristike, a konstrukt validnost je potvrđena preko korelacija sa skalama inventara Velikih pet plus dva.