Department of Psychology

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  • ItemOpen Access
    A multinational study to test the hypotheses of the physical activity adoption and maintenance model (PAAM)
    (Human Kinetics Publ Inc, 2023-05) Jekauc, D.; Gürdere, Ceren; Englert, C.; Strobach, T.; Bottesi, G.; Bray, S.; Brown, D.; Fleig, L.; Ghisi, M.; Graham, J.; Martinasek, M.; Tamulevicius, N.; Pfeffer, I.
  • ItemOpen Access
    Negative speaks louder than positive: negative implicit partner evaluations forecast destructive daily interactions and relationship decline
    (SAGE Publications Ltd, 2023-12-30) Sakman, Ezgi; Zayas, V.
    Romantic relationships are affectively complex. Any given interaction consists of both rewarding and aversive features. Recent work has shown that implicit partner evaluations (IPEs)—evaluations spontaneously triggered when one thinks about one’s partner—are also affectively complex. Does such complexity in IPEs help individuals navigate rewarding and aversive aspects inherent in interactions? The present work examined the proposition that negative IPEs uniquely forecast aversive daily relationship behaviors, whereas positive IPEs uniquely forecast rewarding daily relationship behaviors. Individuals self-identified as in a heterosexual romantic relationship completed measures to assess their implicit and explicit partner evaluations at two time points, spanning a three-month period, as well as a daily diary component. Time-1 negative IPEs forecasted perceiving and enacting negative behaviors during a 14-day daily diary, which, in turn, predicted deterioration in explicit partner and relationship evaluations 3-months later. The predictive ability of negative IPEs remained even after statistically controlling for positive IPEs and explicit evaluations. Positive IPEs were weak and inconsistent predictors of outcomes. The findings shine a spotlight on the differential functions of positive and negative IPEs, the importance of assessing negative IPEs independently from positive IPEs, and the role of negative IPEs in predicting destructive relationship experiences.
  • ItemOpen Access
    What motivates adolescent bystanders to intervene when immigrant youth are bullied?
    (John Wiley and Sons Inc, 2023-01-12) Hitti, A.; Gönültaş, Seçil; Mulvey, K. L.
    Pathways to bystander responses were examined in both generalized and bias-based bullying incidents involving immigrant-origin victims. Participants were 168 (Mage = 14.54, 57% female) adolescents of immigrant (37.5%) and nonimmigrant backgrounds, who responded to their likelihood of intervening on behalf of either an Arab or Latine victim. Models tested whether contact with immigrants and one's desires for social contact with immigrant-origin peers mediated the effects of individual (shared immigrant background, and discriminatory tendencies) and situational (inclusive peer norms) intergroup factors on active bystander responses. Findings indicated that desires for social contact reliably mediated effects across both victims; however, contact with immigrant peers was only associated with responses to Latine victims. Implications for how to promote bystander intervention are discussed.
  • ItemEmbargo
    Domain-general or specific: how is children's understanding of deception socialized?
    (Wiley-Blackwell Publishing Ltd., 2023-09-22) Allen, Jedediah Wilfred Pap; Kara, D.
    The current study investigated parenting influences on children's understanding of lie-telling in eight different social situations. These social situations clustered into two broad categories that have been assumed in the literature: first, self-oriented lies that were generally told to benefit the self (e.g., to avoid punishment or gain status); and second, socio-culturally-oriented lies that were told for more social reasons (e.g., to create positive affect, maintain modesty or politeness). Two types of parenting variables were also measured. The first concerned more general parenting practices and have been studied in the literature; while the second was about more specific parental deceptive behaviors like lying to your child for their compliance. Participants included 141 Turkish parent-child dyads aged 7, 9, and 11. All children judged the self-oriented and the socio-cultural lies as inappropriate but more so for the self-oriented ones; further, the socio-cultural lies were judged less negatively with age. While general parenting practices did not predict children's judgments, for parental deceptive practices, there were strong negative relationships between parents’ use of threatening lies (e.g., “come with me or I'll leave you here”) and children's judgments for both self- and socio-cultural lie types. The two main conclusions are that specific parental deceptive practices are more relevant than general parenting for understanding children's judgments about lie-telling situations. Second, the assumed categorization of lies into “self-” and “social-” seems generally valid when using a plurality of situations. Finally, some issues related to the morality of lie-telling are discussed.
  • ItemEmbargo
    Zebrafish optomotor response to second-order motion illustrates that age-related changes in motion detection depend on the activated motion system
    (Elsevier Inc., 2023-06-10) Karaduman, Ayşenur; Karoğlu-Eravşar, Elif Tuğçe; Kaya, Utku; Aydın, Alaz; Adams, Michelle Marie; Kafalıgönül, Hulusi
    Various aspects of visual functioning, including motion perception, change with age. Yet, there is a lack of comprehensive understanding of age-related alterations at different stages of motion processing and in each motion system. To understand the effects of aging on second-order motion processing, we investigated optomotor responses (OMR) in younger and older wild-type (AB-strain) and acetylcholinesterase (achesb55/+) mutant zebrafish. The mutant fish with decreased levels of acetylcholinesterase have been shown to have delayed age-related cognitive decline. Compared to previous results on first-order motion, we found distinct changes in OMR to second-order motion. The polarity of OMR was dependent on age, such that second-order stimulation led to mainly negative OMR in the younger group while older zebrafish had positive responses. Hence, these findings revealed an overall aging effect on the detection of second-order motion. Moreover, neither the genotype of zebrafish nor the spatial frequency of motion significantly changed the response magnitude. Our findings support the view that age-related changes in motion detection depend on the activated motion system. © 2023 Elsevier Inc.
  • ItemEmbargo
    Effects of tvns location on erps in response to food
    (Oxford University Press, 2023-01) Albayrak S.; Ürgen, Burcu Ayşen; Yanık, H.; Veldhuizen, M.
  • ItemOpen Access
    Caloric restriction reinforces the stem cell pool in the aged brain without affecting overall proliferation status
    (Elsevier BV, 2022-11-01) Erbaba, Begün; Macaroğlu, Duygu; Avcı, N. İlgim Ardıç; Ergül , Ayça Arslan; Adams, Michelle M.
    Overfeeding (OF) and obesity increase the risk for brain aging and neurodegenerative diseases due to increased oxidative stress and neuroinflammation, which likely contribute to cellular dysfunction. In contrast, caloric restriction (CR) is an intervention known for its effects on extending both life- and health-span. In the current study, the effects on the aging brain of two short-term feeding regimens, OF and CR, were investigated. We applied these diets for 12 weeks to both young and aged zebrafish. We performed protein and mRNA level analysis to examine diet-mediated effects on any potential age-related alterations in the brain. Markers implicated in the regulation of brain aging, cell cycle, proliferation, inflammation, and cytoskeleton were analyzed. The most prominent result observed was a downregulation in the expression levels of the stem cell marker, Sox2, in CR-fed animals as compared to OF-fed fish. Furthermore, our data highlighted significant age-related downregulations in Tp53, Myca, and L-plastin levels. The multivariate analyses of all datasets suggested that as opposed to OF, the adaptive mechanisms increasing lifespan via CR are likely exerting their effects by reinforcing the stem cell pool and downregulating inflammation. The data reveal important therapeutic targets with respect to the state of nutrient uptake for the slowing down of the detrimental effects of aging, resulting in a healthy and extended lifespan, as well as lowering the risk for neurodegenerative disease.
  • ItemOpen Access
    Predictors of college students reasoning and responses to gender based social exclusion
    (Springer Dordrecht, 2023-01-05) Herry, E.; Gönültaş, Seçil; Mulvey, K. L.
    This study examines how young adults evaluate gender-based social inclusion and exclusion from academic peer groups. Participants included 199 college students (M$_{age}$ = 19.18; SD = 1.37, Range = 18–25), who made judgments about the acceptability of gender-based social exclusion of female and male peers from a Physics group (a stereotypically masculine field) and bystander responses to gender-based social exclusion. Equitable attitudes and acceptability of gender-based social exclusion were examined as predictors of bystander responses to social exclusion. Findings showed that participants were less likely to see the exclusion of a female as acceptable compared to the exclusion of a male. However, regarding expected bystander intervention, models differed based on condition (exclusion of a male compared to exclusion of a female peer). Specifically, in the female exclusion condition, participants’ gender predicted equitable attitudes, which then predicted expected bystander intervention and ratings of acceptability. In the male exclusion condition, equitable attitudes predicted acceptability, which then predicted expected bystander intervention. These findings have important implications for understanding how to shape inclusive campus climates.
  • ItemOpen Access
    Personality traits prediction model from Turkish contents with semantic structures
    (Springer, 2023-04-23) Kosan, Muhammed Ali; Karacan, Hacer; Ürgen, Burcu Ayşen
    Users' personality traits can provide different clues about them in the Internet environment. Some areas where these clues can be used are law enforcement, advertising agencies, recruitment processes, and e-commerce applications. In this study, it is aimed to create a dataset and a prediction model for predicting the personality traits of Internet users who produce Turkish content. The main contribution of the study is the personality traits dataset composed of the Turkish Twitter content. In addition, the preprocessing, vectorization, and deep learning model comparisons made in the proposed prediction system will contribute to both current usages and future studies in the relevant literature. It has been observed that the success of the Bidirectional Encoder Representations from Transformers vectorization method and the Stemming preprocessing step on the Turkish personality traits dataset is high. In the previous studies, the effects of these processes on English datasets were reported to have lower success rates. In addition, the results show that the Bidirectional Long Short-Term Memory deep learning method has a better level of success than other methods both for the Turkish dataset and English datasets. © 2023, The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.
  • ItemOpen Access
    Disgust sensitivity relates to attitudes toward gay men and lesbian women across 31 nations
    (Sage Publications Ltd., 2021-11-26) Van Leeuwen, F.; Inbar, Y.; Petersen, M. B.; Aarøe, L.; Barclay, P.; Barlow, F. K.; de Barra, M.; Becker, D. V.; Borovoi, L.; Choi, J.; Consedine, N. S.; Conway, J. R.; Conway, P.; Adoric, V. C.; Demirci, Dilara Ekin; Fernández, A. M.; Ferreira, D. C. S.; Ishii, K.; Jakšić, I.; Ji, T.; Jonaityte, I.; Lewis, D. M. G.; Li, N. P.; McIntyre, J. C.; Mukherjee, S.; Park, J. H.; Pawlowski, B.; Pizarro, D.; Prokop, P.; Prodromitis, G.; Rantala, M. J.; Reynolds, L. M.; Sandin, B.; Sevi, Barış; Srinivasan, N.; Tewari, S.; Yong, J. C.; Žeželj, I.; Tybur, J. M.
    Previous work has reported a relation between pathogen-avoidance motivations and prejudice toward various social groups, including gay men and lesbian women. It is currently unknown whether this association is present across cultures, or specific to North America. Analyses of survey data from adult heterosexuals (N = 11,200) from 31 countries showed a small relation between pathogen disgust sensitivity (an individual-difference measure of pathogen-avoidance motivations) and measures of antigay attitudes. Analyses also showed that pathogen disgust sensitivity relates not only to antipathy toward gay men and lesbians, but also to negativity toward other groups, in particular those associated with violations of traditional sexual norms (e.g., prostitutes). These results suggest that the association between pathogen-avoidance motivations and antigay attitudes is relatively stable across cultures and is a manifestation of a more general relation between pathogen-avoidance motivations and prejudice towards groups associated with sexual norm violations.
  • ItemOpen Access
    Cultural correlates of adult attachment dimensions: comparing the US and Turkey
    (Sage Publications, Inc., 2023-11-27) Sakman, Ezgi; Sümer, N.
    Mainstream attachment literature has chiefly employed WEIRD (Western, Educated, Industrialized, Rich and Democratic) samples, yet cross-cultural studies investigating attachment dynamics outside of Western world corroborated universality of the basic tenets of attachment theory and normativity of attachment security. Importantly, these studies revealed country-level differences in the prevalence of insecure attachment tendencies. Of note, this line of work bears the limitation of reducing culture to country and relying on the individualism versus collectivism dichotomy. The present study offers a novel examination of individual-level links between distinct cultural mindsets and distinct attachment orientations. We investigated two community samples (NTurkey = 368, NUSA = 350) from two diverse cultural contexts by employing an assorted battery of cultural value measures, including both overt and covert measures of cultural indicators. Results revealed distinct relationships between attachment anxiety and the interdependent mindset and attachment avoidance and the independent mindset in both cultural contexts. Findings are discussed in light of cultural implications.
  • ItemOpen Access
    Long-term acetylcholinesterase depletion alters the levels of key synaptic proteins while maintaining neuronal markers in the aging zebrafish (Danio rerio) Brain
    (S. Karger AG, 2023-10-04) Karoğlu-Eravsar, Elif Tuğçe; Tüz-Şaşik, Melek Umay; Karaduman, Ayşenur; Keşküş, Ayse Gökçe; Arslan-Ergul, Ayça; Konu, Özlen; Kafalıgönül, Hulusi; Adams, Michelle M.
    Introduction: Interventions targeting cholinergic neurotransmission like acetylcholinesterase (AChE) inhibition distinguish potential mechanisms to delay age-related impairments and attenuate deficits related to neurodegenerative diseases. However, the chronic effects of these interventions are not well described. Methods: In the current study, global levels of cholinergic, cellular, synaptic, and inflammation-mediating proteins were assessed within the context of aging and chronic reduction of AChE activity. Long-term depletion of AChE activity was induced by using a mutant zebrafish line, and they were compared with the wildtype group at young and old ages. Results: Results demonstrated that AChE activity was lower in both young and old mutants, and this decrease coincided with a reduction in ACh content. Additionally, an overall age-related reduction in AChE activity and the AChE/ACh ratio was observed, and this decline was more prominent in wildtype groups. The levels of an immature neuronal marker were upregulated in mutants, while a glial marker showed an overall reduction. Mutants had preserved levels of inhibitory and presynaptic elements with aging, whereas glutamate receptor subunit levels declined. Conclusion: Long-term AChE activity depletion induces synaptic and cellular alterations. These data provide further insights into molecular targets and adaptive responses following the long-term reduction of AChE activity that was also targeted pharmacologically to treat neurodegenerative diseases in human subjects.
  • ItemOpen Access
    Culturally constituted universals: evidential basis of belief matters
    (John Wiley & Sons Ltd., 2023-03-16) Haskaraca, F. N.; Ilgaz, Hande; Bortfeld, H.; Haan, Michelle de; Messinger, D.
    Differences in the sequence with which children pass the tasks in Wellman and Liu's (2004) theory of mind (ToM) battery is increasingly bringing into question the universal and cultural specifics of children's developing understanding of others' minds. Children from China, Iran, and Turkey pass the knowledge access (KA) task of the battery earlier than they pass the diverse beliefs (DB) task (e.g., Selcuk et al., 2018). This pattern is the reverse of what has been documented with children from Australia and the US (e.g., Peterson et al., 2005). This paper presents three studies with Turkish samples that explore the possible reasons for developmental sequence and performance differences in the ToM battery. Study 1 investigated Turkish-speaking adults' judgments of appropriateness for different epistemic verbs as used in the DB and false belief (FB) tasks. Study 2 investigated whether adults' performance (i.e., accuracy, reaction time) on FB tasks were affected by culturally preferred uses of these verbs. Collectively these studies showed that adults found different epistemic language (“guess,” “think,” and the Turkish-specific “falsely think”) to be appropriate for different belief-based tasks. However, there was no difference in adults' performance based on epistemic language. In Study 3, Turkish-speaking preschoolers' performance in belief-related tasks based on variations in epistemic language and epistemic features (i.e., presence of evidence) was investigated. Among five modifications, Turkish children benefited only from a modification that involved the manipulation of the epistemological basis for ambiguous beliefs (i.e., visual evidence for belief).
  • ItemEmbargo
    Motion and form coherence processing in individuals with cerebral visual impairment
    (John Wiley and Sons Inc., 2023-09-02) Merabet, L.B.; Manley, C.E.; Pamir, Zahide; Bauer, C.M.; Skerswetat, J.; Bex, P.J.
    Aim: Using a visual psychophysical paradigm, we sought to assess motion and form coherence thresholds as indices of dorsal and ventral visual stream processing respectively, in individuals with cerebral visual impairment (CVI). We also explored potential associations between psychophysical assessments and brain lesion severity in CVI. Method: Twenty individuals previously diagnosed with CVI (mean age=17 years 11months [SD 5 years 10months]; mean Verbal IQ=86.42 [SD 35.85]) and 30 individuals with neurotypical development (mean age=20 years 1month [SD 3 years 8months]; mean Verbal IQ=110.05 [SD 19.34]) participated in the study. In this two-group comparison, cross-sectional study design, global motion, and form pattern coherence thresholds were assessed using a computerized, generalizable, self-administrable, and response-adaptive psychophysical paradigm called FInD (Foraging Interactive D-prime). Results: Consistent with dorsal stream dysfunction, mean global motion (but not form) coherence thresholds were significantly higher in individuals with CVI compared to controls. No statistically significant association was found between coherence thresholds and lesion severity. Interpretation: These results suggest that the objective assessment of motion and form coherence threshold sensitivities using this psychophysical paradigm may be useful in helping to characterize perceptual deficits and the complex clinical profile of CVI.
  • ItemOpen Access
    Maternal storytelling and reminiscing styles in relation to preschoolers’ perspective-taking abilities
    (Elsevier, 2023-03-28) Kısa, Elif Bürümlü; Şahin, B. A.; Ilgaz, Hande
    This study investigated mothers’ narrative styles across storytelling and reminiscing contexts in relation to preschoolers’ visual, socio-cognitive, and syntactic perspective-taking (PT) abilities. The sample consisted of 120 Turkish mothers and their 3- to 5-year-old children. Mother-child dyads were asked to retell a storybook and to reminisce about an event they experienced in the lab. Children's visual PT, false belief understanding, syntactic PT, and vocabulary were assessed. The results indicated that mothers showed distinct narrative scaffolding styles in each context (storytelling: storyteller and story builder; reminiscing: elicitor, constructor, co-teller). Maternal storytelling styles, but not reminiscing styles were related to children's age. Children of storytellers performed better in syntactic and visual PT tasks than children of story builders, and children of memory elicitors scored higher in visual PT tasks than children of co-tellers. The implications of these findings are discussed within our understanding of how mother-child discourse affects children's socio-cognitive development.
  • ItemOpen Access
    Tilt aftereffect spreads across the visual field
    (Elsevier, 2023-01-09) Gürbüz, Büşra Tuğçe; Boyacı, Hüseyin
    The tilt aftereffect (TAE) is observed when adaptation to a tilted contour alters the perceived tilt of a subsequently presented contour. Thus far, TAE has been treated as a local aftereffect observed only at the location of the adapter. Whether and how TAE spreads to other locations in the visual field has not been systematically studied. Here, we sought an answer to this question by measuring TAE magnitudes at locations including but not limited to the adapter location. The adapter was a tilted grating presented at the same peripheral location throughout an experimental session. In a single trial, participants indicated the perceived tilt of a test grating presented after the adapter at one of fifteen locations in the same visual hemifield as the adapter. We found non-zero TAE magnitudes in all locations tested, showing that the effect spreads across the tested visual hemifield. Next, to establish a link between neuronal activity and behavioral results and to predict the possible neuronal origins of the spread, we built a computational model based on known characteristics of the visual cortex. The simulation results showed that the model could successfully capture the pattern of the behavioral results. Furthermore, the pattern of the optimized receptive field sizes suggests that mid-level visual areas, such as V4, could be critically involved in TAE and its spread across the visual field.
  • ItemOpen Access
    Psychosis endophenotypes: a gene-set-specific polygenic risk score analysis
    (Oxford University Press, 2023-08-14) Wang, B.; Irizar, H.; Thygesen, J. H.; Zartaloudi, E.; Austin-Zimmerman, I.; Bhat, A.; Harju-Seppänen, J.; Pain, O.; Bass, N.; Gkofa, V.; Alizadeh, B. Z.; Van Amelsvoort, T.; Arranz, M. J.; Bender, S.; Cahn, W.; Stella Calafato, M.; Crespo-Facorro, B.; Di Forti, M.; Giegling, I.; De Haan, L.; Hall, J.; Hall, M.; Van Haren, N.; Iyegbe, C.; Kahn, R. S.; Kravariti, E.; Lawrie, S. M.; Lin, K.; Luykx, J. J.; Mata, I.; McDonald, C.; McIntosh, A. M.; Murray, R. M.; Picchioni, M.; Powell, J.; Prata, D. P.; Rujescu, D.; Rutten, B. P. F.; Shaikh, M.; Simons, C. J. P.; Toulopoulou, Timothea; Weisbrod, M.; Van Winkel, R.; Kuchenbaecker, K.; McQuillin, A.; Bramon, E.
    Background and Hypothesis: Endophenotypes can help to bridge the gap between psychosis and its genetic predispositions, but their underlying mechanisms remain largely unknown. This study aims to identify biological mechanisms that are relevant to the endophenotypes for psychosis, by partitioning polygenic risk scores into specific gene sets and testing their associations with endophenotypes. Study Design: We computed polygenic risk scores for schizophrenia and bipolar disorder restricted to brain-related gene sets retrieved from public databases and previous publications. Three hundred and seventy-eight gene-set-specific polygenic risk scores were generated for 4506 participants. Seven endophenotypes were also measured in the sample. Linear mixed-effects models were fitted to test associations between each endophenotype and each gene-set-specific polygenic risk score. Study Results: After correction for multiple testing, we found that a reduced P300 amplitude was associated with a higher schizophrenia polygenic risk score of the forebrain regionalization gene set (mean difference per SD increase in the polygenic risk score: -1.15 μV; 95% CI: -1.70 to -0.59 μV; P = 6 × 10-5). The schizophrenia polygenic risk score of forebrain regionalization also explained more variance of the P300 amplitude (R2 = 0.032) than other polygenic risk scores, including the genome-wide polygenic risk scores. Conclusions: Our finding on reduced P300 amplitudes suggests that certain genetic variants alter early brain development thereby increasing schizophrenia risk years later. Gene-set-specific polygenic risk scores are a useful tool to elucidate biological mechanisms of psychosis and endophenotypes, offering leads for experimental validation in cellular and animal models.
  • ItemOpen Access
    Self-orienting in human and machine learning
    (Nature Research, 2023-08-31) De Freitas, Julian; Uğuralp, Ahmet Kaan; Oğuz-Uğuralp, Zeliha; Paul L.A.; Tenenbaum, Joshua; Ullman, Tomer D.
    A current proposal for a computational notion of self is a representation of one’s body in a specific time and place, which includes the recognition of that representation as the agent. This turns self-representation into a process of self-orientation, a challenging computational problem for any human-like agent. Here, to examine this process, we created several ‘self-finding’ tasks based on simple video games, in which players (N = 124) had to identify themselves out of a set of candidates in order to play effectively. Quantitative and qualitative testing showed that human players are nearly optimal at self-orienting. In contrast, well-known deep reinforcement learning algorithms, which excel at learning much more complex video games, are far from optimal. We suggest that self-orienting allows humans to flexibly navigate new settings.
  • ItemOpen Access
    Passive exposure to visual motion leads to short-term changes in the optomotor response of aging zebrafish
    (Cambridge University Press, 2024-03) Karaduman, Ayşenur; Karaoğlu-Eravşar, Elif Tuğçe; Adams, Michelle M.; Kafalıgönül, Hulusi
    Numerous studies have shown that prior visual experiences play an important role in sensory processing and adapting behavior in a dynamic environment. A repeated and passive presentation of visual stimulus is one of the simplest procedures to manipulate acquired experiences. Using this approach, we aimed to investigate exposure- based visual learning of aging zebrafish and how cholinergic intervention is involved in exposure-induced changes. Our measurements included younger and older wild-type zebrafish and achesb55/+mutants with decreased acetylcholinesterase activity. We examined both within-session and across-day changes in the zebrafish optomotor responses to repeated and passive exposure to visual motion. Our findings revealed short- term (within-session) changes in the magnitude of optomotor response (i.e., the amount of position shift by fish as a response to visual motion) rather than long-term and persistent effects across days. Moreover, the observed short-term changes were age- and genotype-dependent. Compared to the initial presentations of motion within a session, the magnitude of optomotor response to terminal presentations decreased in the older zebrafish. There was a similar robust decrease specific to achesb55/+mutants. Taken together, these results point to short- term (within-session) alterations in the motion detection of adult zebrafish and suggest differential effects of neural aging and cholinergic system on the observed changes. These findings further provide important insights into adult zebrafish optomotor response to visual motion and contribute to understanding this reflexive behavior in the short- and long-term stimulation profiles.
  • ItemOpen Access
    Impaired morphological processing: insights from multiple sclerosis
    (Routledge, 2023-06-13) Boudelaa, S.; Boujraf, S.; Belahcen, F.; Ben Zagmout, M; Farooqui, Ausaf
    Multiple Sclerosis (MS) is a neurological disease characterised by damage affecting large bundles of white matter fibres. Morphological segmentation of complex words (e.g. walked) into stems (walk) and suffixes (∼ed) is thought to depend on intact white matter. We tested the hypothesis that Arabic speaking patients with MS may lose the ability to segment morphologically complex words in a primed lexical decision task using word pairs that shared either a root and a semantic relationship (+R + S, e.g. “AnzAl”–“nuzwl” lowering-landing), a root without semantics (+R–S, e.g. “rtAbp”–“trtyb” monotony-tidying up),a semantic relationship (–R + S, e.g. “xyr”–“nEmp” good-grace), or a phonological relationship (–R + Phon, e.g. “mEdn”–“mEAnd” mineral-stubborn). While healthy controls showed priming by root regardless of semantics and inhibition by phonology, the patients showed facilitation by semantics (+R + S and –R + S), and inhibition by phonology (–R + Phon). These findings are used to adjudicate three contending models of lexical processing.