Browsing by Author "Thomas, Kevin G F"

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    Acute psychosocial stress enhances visuospatial in healthy males
    (SAGE Publications, 2013) Human, Robyn; Thomas, Kevin G F; Dreyer, Anna; Amod, Alysaa R; Wolf, Pedro S A; Jacobs, W Jake
    Previous research demonstrates that stress can disrupt a number of different cognitive systems, including verbal memory, working memory, and decision-making. Few previous studies have investigated relations between stress and visuospatial information processing, however, and none have examined relations among stress, visuospatial memory performance, and planning/ organisation of visuospatial information simultaneously. In total, 38 undergraduate males completed the copy trial of the Rey-Osterrieth Complex Figure Test. Those assigned randomly to the Stress group (n = 19) were then exposed to a laboratory-based psychosocial stressor; the others were exposed to an equivalent control condition. All then completed the delayed recall trial of the Rey-Osterrieth Complex Figure Test. Physiological and self-report measures of stress indicated that the induction manipulation was effective. Our predictions that control participants, relative to stressor-exposed participants, (a) take less time to complete the Rey-Osterrieth Complex Figure Test recall trial, (b) reproduce the figure more accurately on that trial, and (c) show better planning and more gestalt-based organisational strategies in creating that reproduction were disconfirmed. At recall, those with higher circulating cortisol levels (measured post-stress-induction) completed the drawing more accurately than those with lower circulating cortisol levels. Otherwise stated, the present data indicated that exposure to an acute psychosocial stressor enhanced visuospatial memory performance in healthy males. This data pattern is consistent with a previously proposed inverted U-shaped relationship between cortisol and cognition: Under this proposal, moderate levels of the hormone (as induced by the current manipulation) support optimal performance, whereas extremely high and extremely low levels impair performance.
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    An exploration of sociodemographic and psychosocial determinants of cognitive performance in a peri-urban clinic population of people with HIV in Cape Town, South Africa
    (2023) Dreyer, Anna Jane; Joska, John A; Thomas, Kevin G F; Nightingale, Sam
    Introduction. Numerous studies, conducted in many different countries, report that cognitive impairment is highly prevalent in people with HIV (PWH). Such impairment can affect adherence to antiretroviral therapy (ART), and adherence is, in turn, essential for PWH to achieve viral suppression. The gold standard to confirm cognitive impairment is a neuropsychological assessment. However, accurate interpretation of neuropsychological test performance requires consideration of, for instance, how impairment is determined and how accurately the contribution of non-HIV factors to poor cognitive test performance is described. These non-HIV factors include sociodemographic variables (e.g., age, sex, educational attainment), psychosocial variables (e.g., socioeconomic status, food security, quality of life), psychiatric variables (e.g., depression, problematic alcohol use), and other medical co-morbidities. Because many existing studies of PWH do not account for (a) the fact that current quantitative methods for defining cognitive impairment may not accurately reflect HIV-associated brain injury, and (b) possible contributions of non-HIV factors to cognitive test performance, it is possible that the reported prevalence rates of cognitive impairment in PWH are inaccurate (or, at least, do not solely reflect the contributions of HIV disease to the impairment). Another uncertainty in the HIV neuropsychology literature concerns sex differences in the cognitive performance of PWH. Some recent studies suggest that women with HIV (WWH) may present with greater cognitive impairment than men with HIV (MWH). Such a sex difference is of potentially significant concern for South African clinicians because two-thirds of the population of PWH in this country are women. However, there is no definitive empirical evidence regarding whether this sex difference exists to a clinically significant degree (in South Africa, specifically, as well as globally) and what its underlying mechanisms might be. To address the knowledge gaps outlined above, this thesis set out to explore the following aims: (1) investigate sex differences in the cognitive performance of PWH by reviewing the current published literature; (2) determine if sex differences exist in a clinic sample of South African PWH; (3) determine how much variation in reported prevalence rates of HIV-associated cognitive impairment are due to the method used to define impairment, and which method correlates best with MRI biomarkers of HIVrelated brain injury in a South African sample of PWH; (4) investigate the contribution of sociodemographic and psychosocial variables, as well as HIV-disease factors and other medical and psychiatric comorbidities, to cognitive performance in a South African sample of PWH; and (5) investigate associations between cognitive performance and ART adherence in 10 a South African sample of PWH. Each of these aims was explored in a separate study. Hence, this thesis reports on findings from five separate journal manuscripts. Method. Study 1 was a systematic review and meta-analysis summarizing the findings of published studies investigating differences in cognitive performance between WWH and MWH. An extensive systematic search of the literature across several databases found 4062 unique articles of potential interest. After thorough screening of that pool of articles, 11 studies (total N = 3333) were included in the narrative systematic review and 6 studies (total N = 2852) were included in the meta-analysis. Effect sizes were calculated to estimate between-sex differences in cognitive performance, both globally and within discrete cognitive domains. Study 2 investigated sex differences in cognitive performance in a sample of PWH with comorbid MDD (N = 105). All participants were attending community clinics in Khayelitsha, a peri-urban community in Cape Town, South Africa, and were part of a larger research program for a randomised controlled trial of a cognitive-behavioral treatment for ART adherence and depression (CBT-AD). As part of this program, they completed baseline neuropsychological, psychiatric, and sociodemographic assessments. T-tests and multivariable regressions controlling for covariates compared baseline cognitive performance of WWH and MWH, both globally and within discrete cognitive domains. Study 3 applied 20 different quantitative methods of determining cognitive impairment to existing data from a different sample of PWH (N = 148). These individuals had also been recruited from community clinics in Khayelitsha, and had completed a comprehensive neuropsychological assessment and a 3T structural MRI and diffusion tensor imaging (DTI) session. Logistic regression models investigated the association between each method and HIV-related neuroimaging abnormalities. Study 4 again used data from the sample of PWH with comorbid MDD who participated in the larger CBT-AD research program. This study investigated which sociodemographic, psychosocial, psychiatric, and medical variables (as measured at baseline) were associated with baseline cognitive performance. Post-baseline, 33 participants were assigned to CBT-AD and 72 to standard-of-care treatment; 81 participants (nCBT-AD = 29) had a follow-up assessment 8 months post-baseline. This study also investigated whether, from baseline to follow-up, depression and cognitive performance improved significantly more in the participants who had received CBT-AD, and examined associations between post-intervention improvements in depression and cognitive performance. Study 5 assessed ART adherence in the same sample of PWH with comorbid MDD. Mixed-effects regression models estimated the relationship between ART adherence (as measured by both self-report and objective measures, and by degree of HIV viral suppression) with cognitive performance 11 and with other sociodemographic, psychosocial, and psychiatric variables at both baseline and follow-up. Results. Study 1: Analyses suggested that, in terms of overall cognitive functioning, there were no significant differences in cognitive performance between WWH and MWH. However, WWH did perform significantly more poorly than MWH in the domains of psychomotor coordination and visuospatial learning and memory. Additionally, the review suggested that cognitive differences between WWH and MWH might be accounted for by sex-based variation in educational and psychiatric characteristics among study samples. Study 2: Analyses suggested that, in our sample of PWH with comorbid MDD, there were no significant differences in cognitive performance between WWH and MWH. Study 3: Findings suggested that there was marked variation in rates of cognitive impairment (20– 97%) depending on which method was used to define impairment, and that none of these methods accurately reflected HIV-associated brain injury. Study 4: Analyses suggested that less education and greater food insecurity were the strongest predictors of global cognitive performance. Improvement in depression severity was not significantly associated with improved cognitive performance, except in the domain of Attention/Working Memory. Overall, factors associated with cognitive performance were unrelated to HIV disease and other medical factors. Study 5: Analyses identified poor global cognitive performance as a potential barrier to achieving HIV suppression. Conclusion. Taken together, the findings from the five studies contained within this thesis suggest that one oft-mooted sociodemographic influence on cognitive performance in PWH, sex, was not a consistent influence on such performance. However, non-biological (mainly psychosocial and socioeconomic) factors were stronger predictors of cognitive performance in PWH than medical factors (including HIV-disease variables). Current quantitative criteria for defining cognitive impairment in PWH also do not accurately reflect the biological effects of HIV in the brain. The implication of these findings is that research studies may be misclassifying PWH as cognitively impaired and consequently overestimating the prevalence of cognitive impairment in this population. When conducting clinical assessments of PWH, future research studies should measure and consider the strong influence of psychosocial and socioeconomic factors on cognitive test performance. Ideally, a diagnosis of impairment should only be made after a comprehensive clinical assessment that includes a detailed history taking. Overall, we need new criteria for defining cognitive impairment in diverse global populations of PWH. Ideally these criteria should be applicable to both research and clinical settings. Assessing for cognitive impairment among PWH and then providing 12 appropriate support could help achieve viral suppression in patients with non-optimal adherence to ART. At public policy levels, addressing larger psychosocial issues (e.g., food insecurity and low educational attainment) may also help improve cognitive performance in PWH.
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    A cognitive profile of South African children with traumatic brain injury
    (2010) Malgas, Nancy; Thomas, Kevin G F
    Research conducted on pediatric populations have shown that an event such as a traumatic brain injury (TBI) experienced in childhood can lead to persistent neuropsychological deficits months, even years post-injury. However, there still exists a dearth of research on pediatric TBI (pTBI), more so in developing countries like South Africa as most pediatric studies have been conducted on Western populations. This situation underlines the need for more research in the field of pTBI.
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    Hidden victims of HIV/AIDS : the impact of caregiving on elderly caregivers
    (2008) Mangerah, Munirah; Thomas, Kevin G F
    The HIV/AIDS pandemic in South Africa and the concomitant high mortality rate of the middle generation has resulted in an increased number of orphans and vulnerable children (DVCs). The responsibility of care for these children has fallen to the extended family, especially elderly females. This study aimed to explore the impact of caregiving on grandmothers caring for DVCs in two Western Cape townships, and to statistically determine predictors of caregiver burden. Participants (n = 57) were members of a community-based supportive organisation, were grandmother caregivers to at least one grandchild, and lived in a household that was impacted by HIVI AIDS. A quantitative questionnaire, consisting of socio-demographic questions, as well as open-ended questions on participants' experiences within the organisation and of caregiving, was individually administered in Xhosa. The Burden Interview (BI), a standardised scale, was used to measure the impact of caregiving on the grandmothers across five dimensions (health, finances, psychological well-being, social life, and relationships). Descriptive statistical analysis of the socio-demographic questionnaire showed that caregiving occurred in the context of poverty, HIV/AIDS, chronic illness, and multigenerational households. Thematic analysis of the open-ended questions revealed that participants benefited financially and emotionally and gained knowledge and skills through membership of the community organisation. However, caregiving was commonly described as emotionally and physically exhausting. This burden was exacerbated by the age and health status of both caregiver and care-recipient, and behavioural difficulties in the care-recipient. A stepwise multiple regression analysis yielded three factors as significant predictors of burden (Rl = .41): the number of children for which the participant was the primary caregiver; the number of chronically ill people in the household; and the need for assistance with caregiving responsibilities. The latter finding probably implies that those who are the most stressed are most likely to require assistance with care. The findings highlight the important contribution of the elderly in buffering the psychosocial impact of the HIV/AIDS pandemic, sometimes at the expense of their own wellbeing. Policy-makers should consider the unique challenges and contributions of the elderly in this regard.
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    HIV-associated cognitive disorders in children and adolescents: methodological investigations and validating a quick screening tool
    (2019) Phillips, Nicole Justine; Hoare, Jaqueline; Stein, Dan J; Thomas, Kevin G F
    Background Perinatal HIV-infection is associated with both cognitive and functional impairment. Accurate measurement and screening for these conditions is key in ensuring that these vulnerable children and adolescent receive the care they need. Objectives I sought to carry out the following: 1) to undertake a systematic review to determine the cognitive effects of living with HIV in children and adolescents, 2) to determine a statistically sound method for assessing cognitive impairment, 3) to determine the association between cognitive impairment and measures of functional impairment and the relative risk of having functional impairment in the presence of cognitive impairment and 4) to validate a quick screening tool for risk of cognitive impairment in children and adolescents living with HIV. Methods This study was nested within a larger longitudinal study, titled, the Cape Town Adolescent Antiretroviral Cohort (CTAAC). This study is a quantitative cross-sectional study. Each aim led to a study using appropriate methodology. For aim 1; electronic systematic searches where conducted to find relevant literature, which were then assessed by two independent reviewers, data were extracted and then meta-analysed. For aims 2-4; data was collected from research participants enrolled into the CTAAC study. Data scoring, capturing and inferential statistics were conducted in SPSS 25. Results With regards to aim 1, I found that there are both consistencies and inconsistencies in the literature regarding which cognitive domains are most affected by HIV. Findings from the meta-analysis showed that the cognitive domains of executive function, processing speed and working memory are the most affected. With regards to aim 2, I demonstrated statically, that composite cognitive domains scores (as opposed to global scores), were more accurate in detecting HIV-related cognitive differences in adolescents. With regards to aim 3; I found that the functional impairment was strongly and significantly associated with degree of cognitive impairment and that adolescents had an increased risk of having functional impairment if they had cognitive impairment. With regards to aim 4; I demonstrated the statistical validity of the youth International HIV Dementia Scale (y-IHDS) to screen for risk of cognitive impairment in HIV-infected adolescents. The y-IHDS displayed high sensitivity and both positive and negative predictive values for screening for all forms of cognitive impairment. Conclusion Assessment of cognitive and functional impairment in HIV-infected children and adolescents requires special considerations. Methods need to be child/adolescent and time sensitive, and should be contextually appropriate. The methodological approaches and screening tool validated here are a start in addressing these kinds of issues both locally and globally. Neurocognitive disorders are common and can cause clinically significant functional impairment, they are however underrecognized in busy clinical settings. The screening adapted and validated here is an easy to use, quick tool which should be rolled out as part of routine care for all children and adolescents attending antiretroviral (ARV) clinics.
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    The impact of psychosocial stress and biological sex on false recognition memory
    (2010) Henry, Michelle; Thomas, Kevin G F
    Based on the premise that both the hippocampus and pre-frontal cortex are affected by cortisol and involved in declarative memory processes, the current research aimed to confirm that psychosocial stress can lead to increased rates of false recognition memory errors in humans. In addition, it attempted to show that false recognition error rates differ depending on biological sex and the original stimulus type, thus extending and validating the research done by Gallo and colleagues (2004) on material specificity in false memory. Participants in a Stress group (15 males and 13 females) were exposed to a procedure designed to induce mild psychosocial stress, whereas participants in a Relax group (15 males and 14 females) were exposed to a period of relaxation. Salivary cortisol, heart rate, and subjective self-report measures were used to determine participants' stress levels. All participants completed a false memory task, entailing 3 different recognition tests, on 2 consecutive days. Results showed that under both stressful and non-stressful conditions, pictures were better remembered than words, and that this effect was not mediated by biological sex. However, false recognition errors were greater for pictures compared to words, and neither experimental condition nor biological sex mediated this effect. It was also found that the amount of false memory recognition errors made was not affected by the presence of a stressor, as participants in the Stress and Relax groups performed equally. This result is in contrast with previous studies which indicate that false memories increase under stressful conditions. Furthermore, the impact of stress on false memory was not mediated by biological sex, as both male and female participants in the Stress group performed equally. False memory rates increased over a 24- hour retention period in all participants - however the decay of true memory yielded inconsistent results. This was the first study to examine the material specificity of false memory under stressful conditions. It was also the first study to examine whether the amount of false memory errors made under stressful conditions differed between male and female participants. Therefore, the question of whether the material specificity of false memory is affected under stressful conditions and mediated by biological sex remains open for further research. The use of varying false memory paradigms and larger sample populations would help clarify this question.
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    Neuroimaging and behavioral investigation of declarative memory in South African children prenatally exposed to alcohol
    (2018) Lewis, Catherine Elizabeth; Thomas, Kevin G F; Jacobson, Joseph; Jacobson, Sandra W; Meintjes, Ernesta M
    Prenatal alcohol exposure (PAE) is associated with a range of physical, growth, and neurobehavioral deficits characteristic of individuals with fetal alcohol spectrum disorders (FASD). Although declarative memory impairment is a key feature of the neurocognitive profile of FASD, the mechanisms underlying this deficit require further clarification. The aim of this cross-sectional research was to examine, both directly and indirectly (via bottom-up and top-down processes), a critical cognitive mechanism that supports successful declarative memory functioning (viz., memory encoding), in children with FASD. Data were collected from a sample (N = 88) of South African children with and without PAE. In Study I, I used a blocked design functional magnetic resonance imaging (fMRI) paradigm to investigate neural activation during visual perception, a lower-order cognitive process essential to memory encoding. The task elicited bilateral category-specific activation during the visual perception of objects and scenes in all participants. The absence of between-group differences suggests that functional recruitment of brain regions during basic visual perception is less susceptible to the effects of PAE than during higher-order processes supporting memory encoding. In Study II, I used an event-related fMRI paradigm to investigate neural activation during memory encoding itself. All participants demonstrated similar memory performance accuracy and recruited extensive bilateral networks during memory encoding. However, participants with a diagnosis of fetal alcohol syndrome (FAS) or partial FAS (PFAS) activated additional regions associated with attentional function. Within the FAS/PFAS group, higher exposure levels were associated with smaller activation increases in the parahippocampal gyri and greater activation increases in the right hippocampal formation during encoding. Data from this study therefore suggest that children with FAS/PFAS recruited more extensive neural resources to support successful memory encoding during this task. In Study III, I used a behavioral source memory paradigm to investigate higher-order executive processes essential for memory encoding. Despite similar recognition accuracy across all diagnostic groups, participants in the FAS/PFAS group showed impaired memory for source details. This pattern of impairment was only partially mediated by working memory performance. These three studies provide novel clarification of the neural and cognitive mechanisms underlying declarative memory impairments in children with FASD.
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    Prenatal alcohol exposure-related reading and phonological processing deficits mediated by working memory
    (2017) Meiring, Landi-Chantel; Thomas, Kevin G F
    Few research studies have investigated the effects of prenatal alcohol exposure (PAE) on reading ability and/or on phonological processing. Most published studies have only included measures of single-word reading. This choice means those studies may lack ecological validity in that they might not have adequately captured the real-life reading difficulties experienced by individuals with PAE. Furthermore, only a handful have considered the possible mediating roles of those higher-order cognitive functions (e.g., working memory (WM)) that are known to be affected by PAE. The current research employed an extensive battery of phonological processing measures, as well as a reading test that featured measures of reading accuracy, reading rate, and comprehension. A sample of 159 children between 9 and 14 years of age, with varying degrees of PAE, including heavily exposed children and non- or minimally-exposed controls, were tested. The design also considered the potential for a mediating role of WM on performances on these tests. Overall, results showed performance deficits in children with either fetal alcohol syndrome or partial fetal alcohol syndrome on reading comprehension and on four measures of phonological processing, after control for potential confounders. Additional analyses showed that performance within all five of these reading-related domains were at least partially mediated by WM performance. I discuss these results in the context of previous findings in this literature, and describe their implications for reading interventions in children and adolescents with PAE.
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    The relationship between elevated night-time Glucocorticoid activity and dreaming: a perspective on sleep-dependent memory consolidation
    (2017) Timol, Ridwana; Thomas, Kevin G F
    Background. The consolidation of episodic memory is particularly vulnerable to fluctuations in glucocorticoid levels, both during wakefulness and during sleep. Corticosteroid exposure is associated with changes in endogenous glucocorticoid activity, sleep disruption, episodic memory impairment, and reduced hippocampal volume. This dissertation had two primary aims. The first was to explore the relationship between corticosteroid exposure and sleep-dependent memory processes, including dreaming, with special focus on associations between corticosteroid exposure and (a) night-time glucocorticoid activity and (b) sleep organization. The second was to explore the neuroanatomical foundation for these relationships in young adults with asthma. To achieve these aims, I conducted three studies. Methods. Study 1 (N = 68) used a cross-sectional, matched-sample, quasiexperimental design to compare night-time salivary cortisol levels, memory performance preand post-sleep, sleep organization (measured using polysomnography), and dreaming in groups of asthmatics and non-asthmatics with varying degrees of corticosteroid exposure. Study 2 (N = 23) used a double-blind, randomized placebo-control true experimental design to test, in healthy young adults, the effects of a single 25 mg dose of prednisone on the same outcome measures. Study 3 (N = 19) used a quasi-experimental design to compare hippocampal volume of moderate-to-high corticosteroid-exposed asthmatics with that of matched healthy controls. That study also examined the relationship between (a) night-time cortisol levels and hippocampal volume, (b) night-time cortisol levels and declarative memory performance, (c) hippocampal volume and declarative memory performance. All participants were English-speaking university students, aged 18-39 years. Results. Studies 1 and 2 showed that, relative to healthy controls, night-time glucocorticoid activity was elevated and sleep organization was disrupted in corticosteroidexposed individuals. Furthermore, there were significant inverse associations between glucocorticoid activity and (a) the organization of slow wave sleep (SWS) and rapid-eye movement (REM) sleep, (b) performance on both declarative and procedural memory tasks, and (c) the episodic memory content of dreams. There were significant positive associations between (a) the proportions and the organization of SWS and REM sleep and performance on measures of both declarative and procedural memory, and (b) the organization of REM sleep and the episodic content of dreams. Study 3 data analyses detected significantly smaller hippocampal volume in asthmatics relative to controls. Severity of asthma was inversely related to left hippocampal volume, but corticosteroid exposure alone was not. Furthermore, a smaller hippocampus was associated with better memory performance among healthy controls, but not among asthmatics. Conclusions. The association between the organization of SWS and REM sleep and performance on measures of both declarative and procedural memory lends support to the sequential hypothesis of sleep-dependent memory processing. The current findings also suggest that glucocorticoid activity is associated with (a) dream content, (b) the organization of SWS and REM sleep, and (c) post-sleep memory performance after sleep, and that these relationships may intersect. Although asthmatics did not display memory deficits or aberrant dreaming patterns, their hippocampal volume data, patterns of night-time cortisol, and sleep disruptions suggest further investigation is warranted into the implications of subtle HPA-axis dysfunction and consequent atypical brain development on cognitive function and quality of life in asthmatics, whether exposed to corticosteroid treatment or otherwise.
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    The relationship between socioeconomic status and neuropsychological performance in 7-10 year-old South African children
    (2011) Schoeman, Fransien; Thomas, Kevin G F
    Socioeconomic status (SES) plays a significant role in neuropsychological performance, with several empirical research studies reporting that low-SES children score more poorly on cognitive tasks than do high-SES children, even when IQ is statistically controlled. However, cognitive ability is not depressed across the board among low-SES children. Rather, abilities have been linked to specific neurocognitive systems. However, in South Africa there is a lack of local research focusing specifically on the link between SES and children's neuropsychological performance. The aim of the current study, therefore, was to investigate the relationship between SES and neuropsychological performance in a sample of South African children (divided into three SES-based groups) between the ages of 7- and 10-years old, with specific focus on the domains of attention, memory, and executive functioning. In addition, I aimed to provide preliminary normative data, stratified by age and SES, for the test battery used in this study.
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    Relationships between mental health, socioeconomic status and subjective social status in first-year students at four South African universities
    (2010) Fowler, Gillian; Thomas, Kevin G F
    Background and Objective: First-year university students face many challenges during the transition to university. Some of these relate to their background and socio-demographic characteristics and others have to do with the characteristics of the universities they attend. South African first-year students may face even more challenges adjusting to university, which are linked to the country's Apartheid history. This study aimed to explore relationships between mental health, socioeconomic status and subjective social status in first-year students at four South African universities. In particular, the aims were to explore the role of subjective social status and resilience in predicting the adjustment, mental health and general health of first year university students. Method: Participants in the study (n=336) were South African first-year students who were enrolled in first year psychology courses at four universities. Two of the universities were historically advantaged, and two were historically disadvantaged. Data collection took the form an online survey as well as the distribution of printed questionnaires. A demographic questionnaire was used in addition to questionnaires, which measured students' quality of adjustment, mental health, general health, subjective social status, alcohol use and illicit substance use and resilience (Connor- Davidson Resiliency Scale). Results: A series of hierarchical regression analyses indicated that place of residence was an significant predictor of the quality of their adjustment to university (R 2 =.11). Results of the multiple regression analyses also indicated that resilience was a significant predictor of mental health (R 2 = .22) and a significant predictor of general health (R2 = .11) in the sample of first-year students. Conclusion: These findings highlight the importance resilience can play in predicting students' mental and general health during the transition to university. It also highlights the fact that universities should take the opportunity to provide adequate support programmes and create social networks to make the transition to university easier for students who may be at risk for poor adjustment and poor mental health and general health. In particular university residences, which provide a living environment that encourages academic and social interaction and provide a supportive atmosphere, can make the transition to university smoother for first years. 4
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    Young adults' sexual strategies and mating displays in the virtual world: an evolutionary perspective
    (2013) Swanepoel, Tarah; Thomas, Kevin G F; Wolf, Pedro S A
    Life History Theory (LHT) predicts that natural selection favours a degree of developmental plasticity when it comes to sexual strategies and mating displays. Individuals should develop a faster life history strategy (showing, for example, higher mating effort and a preference for a variety of mates) when they are raised in a relatively unstable environment with high extrinsic mortality. In contrast, individuals should develop a slower life history strategy (showing, for example, lower mating effort and a preference for investment in longterm parenting) when they are raised in a relatively stable environment with low extrinsic mortality. Most previous research examining predictions derived from LHT regarding sexual strategies and mating displays has used survey designs and self-report instruments exclusively. The current study represents a departure from such designs in that I used a quasiexperimental design to examine sexual strategies and mating displays in virtual chatrooms, and to test LHT-based predictions about those strategies and displays. Specifically, I tested the hypotheses that, in the chatrooms, individuals would adopt sexual strategies and mating displays reflective of their different life history strategies, and that these behaviours would manifest in the virtual world much like they have been documented to manifest in the real world. I used the Mini-K Short Form questionnaire, a 20-item instrument designed to measure both cognitive and behavioural aspects of life history strategy, to designate undergraduate males (n = 44) and females (n = 47) as having either a fast or a slow life history. Ten separate groups of these participants, each featuring 3-5 men and 4-5 women, then interacted in separate 1-hour online chat sessions. Results showed that LHS accurately predicted the ways in which male and female participants engaged with one another. Furthermore, men that remained consistent in their LHS presentation (i.e., they behaved in ways consistent with what their LHS predicted they should) were more popular among women than men who were not consistent in this presentation. These results demonstrate the power of evolutionary-based theories of sexual interaction to predict sexual strategies and mating displays in online settings. Further, the 'pure' environment of the online platform, without extraneous real-world constraints, provided an opportunity to document and examine sexual strategies and mating displays in new and exciting ways.