Melbourne School of Psychological Sciences - Theses
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ItemIndividual differences in perceptual and cognitive decision-making in response to near identical options( 2019)Every day people deal with the “exploration/exploitation dilemma”: Deciding when to stay with the current option or move to a new one. Most research in the literature focuses on the influence that external variables exert on people’s decisions (e.g., punishments/rewards). However, little is known about how people deal with identical or nearly identical options in the absence of external bias. The general assumption present in both human and animal models is that, in the absence of obvious cost, individuals would naturally explore. This thesis directly tests this assumption in six experimental studies by examining people’s behaviour when facing identical or nearly identical options, both in perceptual and behavioural tasks. Despite the obvious differences existing between behavioural and perceptual tasks, people are essentially making similar decisions (to explore a different option; or to exploit the current option). Hence, the broad hypothesis under investigation is that similar tendencies should be found within the same person, across domains. Furthermore, because the impact of external bias was minimal in the tasks used, any differences in people’s explorative tendencies should be attributed to stable factors, such as personality traits. To this end, we individuated two broad personality frameworks (the Big Five Model and the Schizotypy construct). In Study 1-4 we examined how people deal with the trade-off between exploration and exploitation from a perceptual perspective, by using binocular rivalry (where an observer is faced with identical, and equally valid, perceptual solutions). In Study 1 we demonstrated that people high in the Openness to Experience trait significantly differed from other people in the way they flexibly explored and combined basic visual stimuli. In Study 2 we looked at whether differences existed in people’s tendencies to explore perceptual solutions following changes in transient emotional state (i.e., arousal) and found that general changes in one’s mood, but not specific type of mood, have a significant impact. In Study 3 we examined whether changes in alternations (i.e., fast or slow) between perceptual solutions were associated with stable personality traits and found that slower alternations were associated with Conscientiousness, characterised by self-control and determination. In Study 4 we examined whether abnormalities in the way perceptual stimuli are “flexibly” processed in people with schizophrenia can be similarly found in a non-clinical population. We found that increased schizotypy was associated with an increase of mixed percept during binocular rivalry. Study 5-6 examined how people deal with the trade-off between exploration and exploitation from a behavioural perspective, by using the Virtual Environment task, which was designed and developed specifically for this aim. The Virtual Environment task was inspired by the animal literature (i.e., the optomotor maze; van Swinderen, 2011) where flies need to choose between identical turning points to advance in the maze. Study 5 presents the findings from the six pilot task. Each version was sequentially developed to rule out potential confounding variables, which might have been responsible for the “unusual” stereotypical behaviour that emerged. That is, people displayed exclusively exploitative tendencies, with no exploration. Study 6 presents the findings from the virtual environment task. Here people showed variability in their explorative tendencies, however, against our prediction an increase of exploration was linked to those personality traits capturing self-discipline (Conscientiousness), rather than flexibility and the tendency to engage with possibilities (Openness to Experience). This was the first evidence of important similarities between perception and behaviour in the way people deal with the trade-off between exploration and exploitation. For example, in relation to the number of decisions, or sampling, of the environment. Our findings also highlighted two important issues in the exploration/exploitation literature. First, they cast doubt on the assumption that humans have a “natural drive to explore” in the absence of rewards. As shown in the difficulties to design appropriate stimuli to observe a balance between exploration/ exploitation in the first place. Second, because our findings did not replicate data from the animal literature, they represent a cautionary tale in interpreting findings from the animal model to be considered valid for humans.
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ItemUsing long-wear electroencephalography to ascertain the variability of Lempel-Ziv Complexity (LZc) measures of consciousness( 2019)It has been recently claimed that measures of spontaneous electroencephalography (EEG) signal complexity, such as Lempel-Ziv Complexity (LZc), can provide an index of an individual’s level of consciousness. Research and clinical practice are currently limited to unreliable behavioural and physiological measures to indicate consciousness. Therefore, there is significant urgency for an objective, reliable, brain-based measure of consciousness. EEG complexity measures utilise algorithms from Information Theory to quantify the diversity in spontaneous EEG data. These are being used to measure the diverse neural activity which necessarily underlies conscious experience. LZc assesses the complexity of multi-channel EEG data using a compression algorithm. Studies of LZc typically involve comparing conditions of altered consciousness with periods of conscious wakefulness. These studies suggest that the change in complexity observed is reflective of the change in level of consciousness. However, very little is known about how LZc varies, either with or without a corresponding change in consciousness. The present study utilised portable long-wear EEG to record multi-day, continuous EEG data from two participants (a total of 8 days for Participant 1 and 4 days for Participant 2). Data from each participant was analysed independently. A LZc algorithm was used to compute a complexity value for every non-overlapping 10-second segment. Results demonstrated that, as with previous research, LZc during Wake (14-hours during the day, multiple days per participant) is, on average, higher than during sleep (Stage N1, Stage N2, Slow-Wave-Sleep, and REM sleep). However, there is considerable variation surrounding these means. Visualising LZc across Wake revealed a consistent but wide spread of variability around the mean, with a scattering of low LZc values reflected by a negative skew in the data. This also results in a wide range of possible mean LZc values made available from taking samples (between 1 and 120 minutes in duration) during this period. Although this variability reduces with larger samples sizes, even day-to-day, LZc can significantly differ within a person. Regardless of the source of this variability, its presence causes concern due to the overarching clinical motivations and potential practical applications of this measure. These results suggest that LZc may not be indicative of level of consciousness, as previously claimed. The issues raised and addressed in this study are not unique to LZc, but will apply to all complexity algorithms, current and future. With this study, we have shown that long-duration EEG is a successful framework for identifying variability in a complexity measure of consciousness. This information-rich dataset is uniquely capable of exposing and investigating complexity measures, with the additional insight of observing and analysing complexity across time. This study endeavours to redirect discussions of this field and promote the use of this framework to both acknowledge and empirically address all surrounding issues and assumptions. All complexity measures should undergo reliability testing as both a proof of concept and a proof of practice before being utilised in research or clinical applications.
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ItemWellbeing and functioning in emerging adulthood: A longitudinal study of determinants and mechanisms( 2018)During the key periods of adolescence and emerging adulthood, individuals can be particularly vulnerable to experiencing suboptimal wellbeing and functioning. With potential long-term impacts on adult trajectories, early wellbeing promotion is critical. This study aimed to further understand wellbeing development across adolescence and into emerging adulthood, by examining the role of a range of individual and environmental characteristics. The individual characteristics examined included temperament, anxiety symptoms, and depression symptoms. Environmental characteristics included parental responses to emotion expression, parental mental health, stressful life events, and maltreatment. The role of emotion regulation strategies were also explored in relation to the characteristics and wellbeing. The study utilised a longitudinal community cohort from the Adolescent Development Study, recruited from schools across Melbourne, Australia. The sample included 245 families who completed questionnaires across three time points. At time 1 (mean age = 12.45), measures of temperament, depression symptoms, anxiety symptoms, parental depression symptoms, parental anxiety symptoms, and parental responses to offspring emotion expression were completed. At time 2 (mean age = 15.01), adolescents completed measures of stressful life events and maltreatment. They completed emotion regulation and wellbeing measures at the final time point (mean age = 18.83). Predictor variables were factor analysed within each domain in order to provide sufficient representation of the structure of the data. A series of path analyses, controlling for gender and SES revealed that temperament traits, neglect, and abuse predicted wellbeing and functioning outcomes. Bootstrap path analyses (using 95% confidence intervals for the indirect effect) revealed significant associations between the emotion regulation strategies of rumination, distraction, mindfulness, cognitive reappraisal, and expressive suppression with the individual and environmental characteristics, and wellbeing and functioning outcomes. Findings suggest that wellbeing development across adolescence and emerging adulthood is associated with individual characteristics (e.g., temperament), as well as environmental experiences that deviate from adaptive ranges (e.g., neglect). The various patterns found in the study reinforce the salience of examining wellbeing as a multifaceted construct, with aspects of wellbeing potentially having different developmental pathways. Furthermore, emotion regulation strategies may be important for wellbeing pathways, with maladaptive strategies (e.g., rumination) being associated with lower wellbeing and adaptive strategies (e.g. mindfulness) associated with higher wellbeing. Therefore, emotion regulation may be a suitable target for optimising youth wellbeing.
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ItemBrain and behavioural correlates of emotional voice processing in autism and its broader phenotype( 2019)Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition characterised by impairments in two core domains of social communication deficits and restricted, repetitive behaviours or interests. A milder variant of autism-like characteristics, known as the Broader Autism Phenotype (BAP), is present at higher rates in relatives of individuals with ASD than the general population, indicating a genetic liability for ASD. There is a wealth of social cognitive research documenting theory of mind, empathising, and emotional face processing deficits in ASD and the BAP, which correspond to abnormal brain function in the “social brain”. However, less research has been conducted on the brain and behavioural correlates of emotional voice processing in ASD and the BAP, despite its significance for social cognition. This thesis aimed to profile emotional voice processing abilities in ASD and the BAP in relatives and the general population, specifically relating to non-linguistic vocalisations known as vocal affect bursts (e.g., laughter, cries, screams). This thesis also aimed to identify the neurobiological substrates of emotional voice processing in individuals with ASD and relatives with the BAP. Three studies were performed to address these aims, each using the same purpose-built, web-based and/or functional MRI (fMRI) task to assess behavioural performance and elicit brain activation. Whole-brain activation elicited by the fMRI task was assessed using random- and fixed-effects analyses (RFX and FFX), which allowed inferences to be made on the population and sample levels, respectively. Study 1 examined vocal affect burst recognition and its neurobiological correlates in individuals with high-functioning ASD (n = 16) compared to typically-developing controls (n = 16). The ASD group demonstrated a vocal emotion recognition deficit on the web-based task, where they misclassified neutral non-linguistic voices as expressing basic emotions at a higher rate than controls. RFX analyses revealed no significant group differences in brain activation, whereas FFX analyses revealed that the ASD group demonstrated higher activation relative to controls in widely distributed regions associated with emotional voice processing, executive function, memory, motor and somatosensory processing, and visual processing. These findings enable atypical brain activation to be inferred for this specific ASD cohort, but not for the wider ASD population. Although cohort-specific, such information may facilitate hypothesis generation for future investigations of neurobiological compensation in ASD. Study 2 addressed the same research questions as Study 1 in relatives of individuals with ASD (n = 13) who were determined to have the BAP on clinical assessment. The BAP group demonstrated no vocal emotion recognition deficit relative to controls (n = 13) on the web-based task. Under FFX analyses alone (not RFX analyses), the BAP group demonstrated significantly higher activation in the left lateral occipital cortex relative to controls. Inferences about the FFX findings are limited to the specific BAP cohort assessed here, and cannot be extended to the wider population of ASD-relatives with the BAP. Nonetheless, these findings may inform new hypotheses exploring endophenotypes (i.e., intermediate phenotypes) of ASD, characterised by a similar expression of neurobiological compensation in ASD and the BAP. Study 3 used the web-based task to assess the association between vocal affect burst recognition and the continuous distribution of BAP traits in the general population of individuals without a family history of ASD. It was hypothesised that lower recognition accuracy for the six basic emotions would correlate with higher self-ratings of BAP traits. In contrast to expectations, higher classification accuracy (and emotional intensity ratings) for angry voices correlated significantly with higher self-ratings of rigid BAP traits. The specific anger-rigid association indicates that enhanced auditory threat detection constitutes an aspect of the BAP in the general population. Further research is recommended to examine whether this relationship is mediated by underlying personality factors like neuroticism or trait anxiety. Overall, different behavioural profiles of emotional voice processing abilities were observed in individuals with ASD (deficit—misclassifying neutral voices as being emotional), relatives with the BAP (no deficit—intact performance), and individuals from the general population with higher levels of BAP traits (advantage—enhanced sensitivity to angry voices). The neuroimaging findings of enhanced activation in the specific ASD and BAP cohorts assessed here may have implications for future research investigating the role of neurobiological compensation for emotional voice processing in their respective populations, potentially including the exploration of endophenotypes of ASD. Such studies would ideally include larger ASD and BAP (relatives) samples that enable the assessment of more homogenous, identifiable subgroups who may be susceptible to increased cognitive demands for emotional voice processing. This thesis extends research on social cognition within the voice modality in ASD and the BAP, and may have wider implications for understanding the genetic aetiology of social communication impairments in ASD.
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ItemIs the mental number line a unique model of numerical cognition?( 2019)Many theories of number propose that humans possess a ‘mental number line’ (MNL) representation. The MNL is commonly measured with a number-to-position (NP) task, and this task is often used to make inferences about the MNL representation. However, most research on MNL representations to date has made assumptions about the properties of the MNL without considering the role of ordinal relationships between numbers. The research reported in this thesis examined whether the MNL metaphor should be extended to include ordinal relationships, and to examine the nature of these relationships. A pilot study tested whether a linear MNL representation could be shifted with logarithmic training. Adults completed a series of logarithmic feedback sessions, and their NP task performance was assessed at the end of each training block. Findings revealed little to no systematic effect of logarithmic training on NP task performance, despite participants successfully learning the logarithmic function. They also revealed individual differences in the overall impact and learning of the logarithmic feedback. These findings suggested that relationships between numbers may change to allow accurate task performance, which may not be reflected in the NP task. Study 1 tested whether the linear response profile that describes NP performance is specific to number, or whether this pattern of responding is a feature of ordered lists more generally. Adults were given NP and alphabet-to-position tasks. Findings showed that numbers and letters both displayed similar linear trends. This suggested that the linear profiles attributed to number may reflect the way in which ordinal lists of symbols are learned. Studies 2a and 2b investigated whether leaning a list of novel symbols is mediated by the underlying spatial properties of the symbols (e.g., spatial complexity). Novel symbols were used to minimise the overlearned nature of Hindu-Arabic numerals. Study 2a aimed to determine the ideal novel symbol set to use in Study 2b, specifically, one which could be ordered by complexity. Participants made judgements on two novel symbol sets, and their relationship to a range of numerical stimuli. In Study 2b, a paired comparisons training method was used to teach participants the order of a list of novel symbols. Participants were allocated to either a spatial complexity or a random complexity condition, and made judgements regarding which of two symbols was numerically ‘larger’. When novel symbols were ordered by spatial complexity, learning was facilitated. These findings showed that the spatial complexity and relational information of symbols may mediate the construction of ordered representations. This suggests that a common cognitive representation underlies all ordinal lists. Overall, the findings of this research indicate that a more nuanced account of the MNL representation is required, particularly in terms of ordinal relationships between numbers. The findings also suggest that the NP task measures ordinal lists more generally. Arguably, the way in which ordered lists are learned, combined with the relative relationships between symbols, may account for performance on the NP task, and the MNL metaphor should be extended to account for these ordinal relationships.
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ItemThe Relationship Between Executive Function and Bilingual Language Control( 2019)Many contemporary proposals of bilingualism conjecture that domain-general Executive Functions (EFs) are fundamental to language control. These proposals revolve around two main observations: the first is that bilinguals have been shown to demonstrate superior performance on tasks used to measure non-linguistic EFs, and the second is that language switching superficially appears to relate to switching between tasks (a process which has been associated with EFs) in that they both induce a Response Time (RT) cost. Critically, direct evidence for the involvement of EFs in both non-linguistic and linguistic bilingual processing have not been demonstrated, but merely speculated. In this thesis, I present a series of four analyses, where I explicitly investigate the presence of EFs in bilingual processing by expressing their impact as a set of cognitive model parameter changes to task performance. The results reveal that bilingual behaviour across both the non-linguistic and linguistic domains do not exhibit signs of EFs, but instead demonstrate the influence of other lower-level general cognitive processes. The main conclusions of this thesis are as follows: A) the putative bilingual advantage is attributed to enhanced selective attention and B) language switches are attributed to automatic bindings between language information and response. These findings are discussed in terms of their implications for current frameworks of language control and bilingualism in general.
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ItemAre personality traits contextualised? Effects of situational characteristics on the manifestation of trait expressions( 2019)Personality traits are the main currency of the field of personality psychology. However, historically there has been much confusion concerning the conceptualization of traits in relation to context, which remains unclear to date. Some personality psychologists have proposed that traits are internal and decontextualized dispositions that account for consistency in behaviour and experience across time and situations, whereas others have argued that traits are patterns of behaviour and experience that are contextualized and require appropriate eliciting stimuli for manifestation. Although there is a long history of research on the interplay of traits and situations, the contextualized view has received little attention and not yet been systematically examined in empirical studies. This thesis aims to evaluate the contextualized view of traits, and to clarify what is meant exactly when describing someone as high or low on a personality trait, specifically in relation to context. When we call someone an ‘extravert’, are we describing their typical patterns of behaviour and experience across all contexts, or are we describing their typical patterns of behaviour and experience in particular contexts? Among all traits, extraversion and neuroticism are perhaps the best understood in terms of eliciting stimuli—reward and threat, respectively— which have been described and incorporated in several personality theories. For this reason, they are the focus of this thesis. It is expected that traits will predict their corresponding expressions most strongly within situations containing relevant eliciting stimuli. The hypotheses were: (a) the relation between trait extraversion and patterns of state extraversion would be the strongest within contexts characterized by rewarding stimuli; and (b) the relation between trait neuroticism and patterns of state neuroticism would be the strongest within contexts characterized by threatening stimuli. A collection of four studies were designed to examine the contextualized nature of extraversion and neuroticism using different methodologies. The first study was an online survey, examining the hypotheses by asking participants to imagine their behaviour in certain context, the second one in a controlled lab environment, and the third and the fourth studies in people’s everyday life context using experience sampling methods. Across these studies, a mixture of subjective and objective measures of personality states and situations were employed. All four studies showed that extraversion and neuroticism significantly predicted state extraversion and state neuroticism, respectively, across all contexts. Meanwhile, state extraversion was significantly higher in rewarding contexts and state neuroticism was significantly higher in threatening contexts—both within-person and between-persons. However, the magnitude of the relation between trait and state extraversion, or between trait and state neuroticism, did not vary strongly across contexts. Although the results differed slightly depending on the study, the trait (extraversion vs. neuroticism), and the measure used (subjective vs. objective situation ratings), overall there was very weak evidence that trait-state associations vary across context. These findings therefore suggest trait extraversion and neuroticism are not strongly contextualized. These findings have broad theoretical implications for understanding what a trait is in relation to context. Additionally, some findings may have theoretical implications for how traits influence experiences of situations via situation perception and selection processes. Some practical implications concern the use of situation reappraisal as a coping strategy to improve people’s functioning in different contexts. Future studies could extend this thesis by examining the contextualized view in relation to other trait domains, aspects, and facets. They could also explore personality’s effects on situations more rigorously to disentangle the various mechanisms concerned with situation perception, situation selection, situation transformation, and situation evocation. Furthermore, they could apply these understanding to improve people’s wellbeing and facilitate personality change.
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ItemIs there a non-symbolic SNARC-like effect?( 2019)It is claimed that numbers are represented spatially. Evidence for this claim comes from the Spatial-Numerical Association of Response Codes (SNARC) effect. In the symbolic number SNARC effect, faster responses are found for the left/right hand for numerical judgments when a presented target number is smaller/larger than a referent. Yet little research has examined whether a SNARC-like effect is evident for non-symbolic quantities. If a non-symbolic SNARC-like effect can be demonstrated it would suggest that non-symbolic quantity is also represented spatially. This is an important issue conceptually because it may inform claims about the neurocognitive representation of symbolic number and non-symbolic quantity in the brain. The limited research that has examined the non-symbolic SNARC-like effect has used stimuli that could be translated into symbolic terms or has ignored the potential effects of individual differences by collapsing data across magnitudes during analysis. These methodological issues were addressed in the research reported in this thesis in which the results of five studies are reported to determine whether a SNARC-like effect occurs for non-symbolic stimuli. In Study 1 adults (n = 28) judged whether the quantity of a target array of dots was smaller or larger than a referent array of dots using either their left or right hand to make judgments. The referent was always 30-dots and judgment reaction times (RTs) to six different target arrays were assessed (i.e., 15, 20, 25, 36, 45 or 60-dots). Participants also completed a visuo-spatial memory (VSWM) and a math ability task. A non-symbolic SNARC-like effect was observed but no relationship between this effect and VSWM or math ability was found. The rationale of Study 2A was to reduce issues of discrimination and calibration found in Study 1 by reducing task difficult. Thereby increasing the chance of finding a non-symbolic SNARC-like effect for all participants. To investigate the degree to which the non-symbolic SNARC-like effect is affected by the ratio between the referent and target arrays, in Study 2A adults (n = 26) compared target arrays that were either 15 or 60 dots with a referent array of 30 dots (i.e., ratios of 0.5). They also completed VSWM and math tasks. A non-symbolic SNARC-like effect was observed which was related to VSWM. Participants who showed a more pronounced non-symbolic SNARC-like effect showed better VSWM performance. Study 2B investigated if a more pronounced non-symbolic SNARC-like effect occurs for targets closer in magnitude to the referent. The rationale was to see whether, as in the symbolic SNARC effect, non-symbolic quantity stimuli that result in slower RTs tend to elicit a stronger SNARC-like effect. The referent was 30 dots and the target arrays either 20 or 45 dots (ratios of 0.66). Adults (n = 39) completed the non-symbolic judgment, VSWM, and math tasks. Compared to Study 2A, a more pronounced non-symbolic SNARC-like effect was found. The symbolic SNARC effect has been found for other response modalities (i.e. eyes, feet). Study 2C (n = 18, adults) aimed to determine if the non-symbolic SNARC-like effect transfers to another response modalities (i.e. feet) and the degree to which responses are influenced by the surface area of the dot stimuli, in Study 2C referent and target dot arrays had the same total surface area. A non-symbolic SNARC-like effect was found in this study, which suggests that total dot surface area was not the driver of the SNARC effect found in Experiments 1, 2A, 2B and 2C. The rationale for Study 3 was to specifically address individual differences in calibration and discrimination for the non-symbolic SNARC-like effect found in Studies 1 and 2. Study 3 (n = 87) aimed to investigate the claim that individual differences in the Weber fraction may explain non-symbolic SNARC-like effect judgments using an adaptive staircase to measure the Weber fraction. This Weber threshold was then used calibrate the optimal ratio of referent-to-target for each participant. In the non-symbolic quantity judgment task one of six referents (10, 20, 30, 40, 50 or 60 dots), each being paired with an ‘easy’ (twice threshold) and a ‘hard’ (at threshold) (n = 11 – 100 dots) target. However, findings did not support this claim as participants with low and high-performance numerical acuity showed a similar non-symbolic SNARC-like effect. The findings showed a consistent non-symbolic SNARC-like effect. The pattern of findings suggests the non-symbolic SNARC-like effect is robust as it was shown across all five studies and was resistant to manipulations of ratio, visual cues, and modality of response. Differences in discrimination and calibration were found for numerical judgments suggesting there are individual differences in the spatial representation of non-symbolic quantities. Moreover, individual differences in the spatial representation of non-symbolic quantities may be related to structural differences in the brain. This confirms the importance of the non-symbolic SNARC-like effect for models of numerical cognition providing evidence that non-symbolic quantity is represented spatially from smallest to largest, left to right akin to a symbolic mental number line. This suggests that neurocognitive systems may represent symbolic number and non-symbolic quantity in the brain in a similar manner. This finding has potential implications for education and interventions for those with dyscalculia.
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ItemInvestigating the construct validity of contemporary cognitive assessment( 2019)Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV) is the most commonly used instrument for the assessment of cognitive abilities, and in making high-stakes decisions in Australia. The current thesis comprises four studies related to the validity of using WAIS-IV in cognitive assessment. The norms for the WAIS-IV used in Australia are based on the US standardization sample. The Woodcock Johnson III (WJ III) battery has been normed for Australian population under the age of 22. This study investigated the score equivalence of the WAIS-IV and the WJ III cognitive test battery in an Australian university student sample. One hundred and sixty-four participants, of whom 38 undertook both tests, were assigned to tests in a blocked, random order. Scores from all, and from those aged less than 22 years, were analysed. The Full Scale Intelligence Quotient of the WAIS-IV was significantly higher than the WJ III General Intellectual Ability score in every analysis. The effect sizes were medium and large in the independent and repeated measure analyses respectively. We argue for norming of the WAIS-IV, or any test used for high-stakes assessment, for Australian population to ensure fairer decisions. In the second study a five-factor model was found that fitted the WAIS-IV U.S. 15-indicator standardization samples for the nine age-groups between 16 and 69 years (N for each group = 200). A strong metric invariance for three of the five factors and a partial intercept invariance for the remaining two was established. Pairwise comparisons of adjacent age groups supported the inference that cognitive-trait group differences are manifested by group differences in the test scores. The third study sought a common model for a clinical sample of scores (N= 321) and the standardization samples. The clinical sampled differed from the standardization samples in that (a) the heterogeneous clinical sample comprised scores from patients, aged 16 to 91, with disparate neurological diagnosis in contrast to the nine age-group stratified standardization samples, (b) only the 10 core subtests were administered in the clinical sample, and (c) the clinical sample had missing data. We found (a) a difference in response strategy between the clinical and non-clinical sample, but (b) a weak factorial invariance of a five-factor measurement model across the clinical and standardization samples. We argue that the results do not disconfirm the hypothesis that the same five latent abilities found in the analysis of the 15 subtest scores in the standardization samples underlie the scores in the clinical population. In the fourth study six models from prior studies were used to generate Monte Carlo simulation data to assess sampling variation in outcomes when model misspecification is restricted to the alternate models canvassed for WAIS-IV. We found that (a) the fit of most models to samples from the different populations were good, (b) the estimated value of a parameter unrelated to the variables germane to the misspecification is true to the population value, (c) increased sample size slightly improved RMSEA, and had minimal effect on parameter estimates, (d) the average fit measures in estimations with and without warnings were not different, (e) the number of replications had minimal effect on the fit and the estimated parameter values. The results suggest that (a) post hoc modification to improve fit in a single sample is difficult to justify, (b) even in an ill-fitting model the estimates of parameters unrelated to the misspecification may be accurate, and (c) theoretical insight and heuristic reasoning aid the identification of problematic parameters.
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ItemImplications of different patterns of non-symbolic and symbolic magnitude representations for children’s mathematical abilities( 2019)It has been argued that early math ability rests on two core, putatively innate, number systems: a precise small number system that allows an accurate and rapid apprehension of the numerosity of small sets (i.e., subitizing), and an approximate magnitude representation that allows discrimination between quantities. Moreover, differences in core number systems functioning are claimed to underlie differences in math ability. It is, furthermore, claimed that non-symbolic magnitude representations scaffold symbolic magnitude representations and ipso facto, math abilities. While these claims are frequently made, evidence in support of them is less than convincing. One difficulty in clarifying the relationships between the two magnitude representations, or core number and maths abilities, is the large inter-individual variation in these abilities in young children which may obscure the relationships between them. Most research that has examined this issue has used variable-oriented analytic methods that treat variance as error or noise. It is proposed herein that using a person-centred analytic method (i.e., latent profile modelling) to explicate the variance may allow identification of different ability patterns (latent profiles) that reside within the overall variance distribution and, in turn, provide a more nuanced developmental model of numerical cognition. To this end, three studies were conducted that focus on the significance of different patterns of non-symbolic–symbolic magnitude representations (Studies 1 and 2), and the relationship between these patterns and different patterns of the apprehension of small sets (Study 3). In Study 1(a), 124 five- to seven-year-old children completed non-symbolic and symbolic magnitude judgement tasks, cognitive measures often associated with math ability (visuo-spatial working memory [VSWM], naming Hindu-Arabic numbers and processing speed) as well as transcoding, and a single digit addition (SDA) test. A latent profile analysis (LPA) of the magnitude judgment accuracies and response times revealed four different patterns of non-symbolic–symbolic magnitude ability relationships residing within the overall variance distribution. The cognitive measures were related to the four profiles in different ways; and the profiles predicted differences in SDA and transcoding abilities. In Study 2(b), a partial replication of Study 1, 109 five- to six-year-old children completed the same tasks as Study 1 twice–one year apart. Latent transition analysis, a longitudinal extension of LPA, examined change and stability patterns in the four profiles over time. Similar to Study 1, the findings showed the patterns were differentially associated with cognitive and math abilities. Study 3 examined the relationship between non-symbolic–symbolic magnitude ability patterns and small precise number ability patterns. The findings replicated those of Studies 1 and 2, and also showed an overlap in the two core number abilities. While only VSWM and magnitude ability patterns predicted SDA abilities (over and above small precise number abilities); both magnitude ability and small precise number ability patterns predicted single-digit subtraction abilities over and above the other cognitive factors. In summary, the findings reported herein confirm the existence of different magnitude ability relation patterns which are differentially associated with different cognitive and math abilities. Examining the change/stability pathways in these ability patterns may reveal typical and atypical pathways of math development. It is evident that different magnitude ability relation patterns partially overlap with the small precise number ability patterns. Nonetheless, differences in the patterns in the two core number indices, along with differences in cognitive indices, predict different math abilities (i.e., single-digit addition and subtraction). The overall pattern of findings is discussed in terms of a more nuanced model of numerical cognition, as well as the value of the findings for specifying diagnostic markers of early math difficulties. (a) Chew, C. S., Forte, J. D., & Reeve, R. A. (2016). Cognitive factors affecting children’s nonsymbolic and symbolic magnitude judgment abilities: A latent profile analysis. Journal of Experimental Child Psychology, 152, 173-191. https://doi.org/10.1016/j.jecp.2016.07.001 (b) Chew, C. S., Forte, J. D., & Reeve, R. A. (2019). Implications of change/stability patterns in children’s non-symbolic and symbolic magnitude judgement abilities over one year: A latent transition analysis. Frontiers in Psychology, 10, 441. https://doi.org/10.3389/fpsyg.2019.00441