Melbourne School of Psychological Sciences - Research Publications
Permanent URI for this collection
Search Results
1 - 4 of 4
-
ItemTracking dynamic adjustments to decision making and performance monitoring processes in conflict tasks( 2019-12-20)How we exert control over our decision-making has been investigated using conflict tasks, which involve stimuli containing elements that are either congruent or incongruent. In these tasks, participants adapt their decision-making strategies following exposure to incongruent stimuli. According to conflict monitoring accounts, conflicting stimulus features are detected in medial frontal cortex, and the extent of experienced conflict scales with response time (RT) and frontal theta-band activity in the electroencephalogram (EEG). However, the consequent adjustments to decision processes following response conflict are not well-specified. To characterise these adjustments and their neural implementation we recorded EEG during a modified Flanker task. We traced the time-courses of performance monitoring processes (frontal theta) and multiple processes related to perceptual decision-making. In each trial participants judged which of two overlaid gratings forming a plaid stimulus (termed the S1 target) was of higher contrast. The stimulus was divided into two sections, which each contained higher contrast gratings in either congruent or incongruent directions. Shortly after responding to the S1 target, an additional S2 target was presented, which was always congruent. Our EEG results suggest enhanced sensory evidence representations in visual cortex and reduced evidence accumulation rates for S2 targets following incongruent S1 stimuli. Results of a follow-up behavioural experiment indicated that the accumulation of sensory evidence from the incongruent (i.e. distracting) stimulus element was adjusted following response conflict. Frontal theta amplitudes positively correlated with RT following S1 targets (in line with conflict monitoring accounts). Following S2 targets there was no such correlation, and theta amplitude profiles instead resembled decision evidence accumulation trajectories. Our findings provide novel insights into how cognitive control is implemented following exposure to conflicting information, which is critical for extending conflict monitoring accounts.
-
ItemNo Preview AvailableUsing a Developmental Test and Electroencephalography to Examine Child Cognition and Its Predictors in Bangladesh (P13-024-19).(Elsevier BV, 2019-06)Objectives: The majority of global health studies use behavioural assessments to measure early child development. Few studies have examined neural indices of cognition using electroencephalography (EEG) in low-income settings. Using data from the Benefits and Risks of Iron Supplementation in Children (BRISC) trial, we examined cognitive development and neural indices of memory and attention in 11 month-old Bangladeshi children and their environmental, socio-demographic, and biological predictors. Methods: At 8 months of age, 3300 children were randomized to iron syrup, multiple micronutrient supplementation, or placebo for 3 months. The main trial outcomes include child development measured using the Bayley Scales of Infant and Toddler Development (BSID)-III, anthropometry, haemoglobin, morbidity, and iron indices. EEG is being conducted to measure event-related brain potentials (ERPs) in a random subset of 250 children at 11 months of age. ERPs are measured in response to auditory and visual stimuli, using roving oddball and attention orienting tasks. Generalized linear mixed models estimated the predictors of BSID-derived cognitive development and EEG-derived neural indices of memory and attention. Potential predictors include psychosocial stimulation, anthropometry, haemoglobin, socio-economic status, food security, sex, and parental education. Additionally, we examined correlations between the BSID cognitive scores and EEG-derived neural indices of cognition. Results: Preliminary BSID data up to December 2018 indicates that 1749 children have completed measurements at 11 months of age. Psychosocial stimulation was significantly associated with BSID cognitive development scores. ERPs in children at 11 months of age are expected to be completed by May 2019 and relevant results will be presented. Conclusions: This study is the first to acquire ERP data in children at 11 months of age in rural Bangladesh. Our findings will identify significant predictors of cognitive functioning measured using the BSID (a well-established developmental test) and using EEG (a sensitive neurophysiological approach) in young children in this setting. Results will indicate the agreement between child cognition outcomes using the BSID and EEG. Funding Sources: NHMRC and The University of Melbourne.
-
ItemThe Decision Decoding ToolBOX (DDTBOX) - A Multivariate Pattern Analysis Toolbox for Event-Related Potentials(HUMANA PRESS INC, 2019-01)In recent years, neuroimaging research in cognitive neuroscience has increasingly used multivariate pattern analysis (MVPA) to investigate higher cognitive functions. Here we present DDTBOX, an open-source MVPA toolbox for electroencephalography (EEG) data. DDTBOX runs under MATLAB and is well integrated with the EEGLAB/ERPLAB and Fieldtrip toolboxes (Delorme and Makeig 2004; Lopez-Calderon and Luck 2014; Oostenveld et al. 2011). It trains support vector machines (SVMs) on patterns of event-related potential (ERP) amplitude data, following or preceding an event of interest, for classification or regression of experimental variables. These amplitude patterns can be extracted across space/electrodes (spatial decoding), time (temporal decoding), or both (spatiotemporal decoding). DDTBOX can also extract SVM feature weights, generate empirical chance distributions based on shuffled-labels decoding for group-level statistical testing, provide estimates of the prevalence of decodable information in the population, and perform a variety of corrections for multiple comparisons. It also includes plotting functions for single subject and group results. DDTBOX complements conventional analyses of ERP components, as subtle multivariate patterns can be detected that would be overlooked in standard analyses. It further allows for a more explorative search for information when no ERP component is known to be specifically linked to a cognitive process of interest. In summary, DDTBOX is an easy-to-use and open-source toolbox that allows for characterising the time-course of information related to various perceptual and cognitive processes. It can be applied to data from a large number of experimental paradigms and could therefore be a valuable tool for the neuroimaging community.
-
ItemEvent-Related Potentials in Relation to Risk-Taking: A Systematic Review(FRONTIERS MEDIA SA, 2018-06-19)Event-related potentials (ERPs) have been used to investigate neural mechanisms underlying risk-related decisions over the last 16 years. We aimed to systematically evaluate associations between risk-taking and ERP components elicited during decisions and following feedback. A total of 79 articles identified from PsychINFO and PubMed databases met the inclusion criteria. Selected articles assessed early ERP components (feedback-related negativity/FRN, error-related negativity/ERN, and medial frontal negativity/MFN) and the mid-latency P3 component, all using gambling paradigms that involved selecting between choices of varying risk (e.g., Iowa Gambling Task, Balloon Analogue Risk Task, and two-choice gambling tasks). The P3 component was consistently enhanced to the selection of risky options and when positive feedback (as compared to negative feedback) was provided. Also consistently, the early negative components were found to be larger following feedback indicating monetary losses as compared to gains. In the majority of studies reviewed here, risk was conceptualized in the context of simple economical decisions in gambling tasks. As such, this narrow concept of risk might not capture the diversity of risky decisions made in other areas of everyday experience, for example, social, health, and recreational risk-related decisions. It therefore remains to be seen whether the risk-sensitivity of the ERP components reviewed here generalizes to other domains of life.