Browsing by Author "Parris, Benjamin"

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    Assessing stimulus–stimulus (semantic) conflict in the Stroop task using saccadic two-to-one color response mapping and preresponse pupillary measures
    (The Psychonomic Society, Inc, 2015-08-14) Hasshim, Nabil; Parris, Benjamin
    Conflict in the Stroop task is thought to come from various stages of processing, including semantics. Two-to-one response mappings, in which two response-set colors share a common response location, have been used to isolate stimulus–stimulus (semantic) from stimulus–response conflict in the Stroop task. However, the use of congruent trials as a baseline means that the measured effects could be exaggerated by facilitation, and recent research using neutral, non-colorword trials as a baseline has supported this notion. In the present study, we sought to provide evidence for stimulus– stimulus conflict using an oculomotor Stroop task and an early, preresponse pupillometric measure of effort. The results provided strong (Bayesian) evidence for no statistical difference between two-to-one response-mapping trials and neutral trials in both saccadic response latencies and preresponse pupillometric measures, supporting the notion that the difference between same-response and congruent trials indexes facilitation in congruent trials, and not stimulus–stimulus conflict, thus providing evidence against the presence of semantic conflict in the Stroop task. We also demonstrated the utility of preresponse pupillometry in measuring Stroop interference, supporting the idea that pupillary effects are not simply a residue of making a response.
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    An fMRI Study of Response and Semantic Conflict in the Stroop Task
    (Frontiers in Psychology, 2019-10-31) Parris, Benjamin; Wadsley, Michael; Hasshim, Nabil; Benattayallah, Abdelmalek; Augustinova, Maria; Ferrand, Ludovic
    An enduring question in selective attention research is whether we can successfully ignore an irrelevant stimulus and at what point in the stream of processing we are able to select the appropriate source of information. Using methods informed by recent research on the varieties of conflict in the Stroop task the present study provides evidence for specialized functions of regions of the frontoparietal network in processing response and semantic conflict during Stroop task performance. Specifically, we used trial types and orthogonal contrasts thought to better independently measure response and semantic conflict and we presented the trial types in pure blocks to maximize response conflict and therefore better distinguish between the conflict types. Our data indicate that the left inferior PFC plays an important role in the processing of both response and semantic (or stimulus) conflict, whilst regions of the left parietal cortex (BA40) play an accompanying role in response, but not semantic, conflict processing. Moreover, our study reports a role for the right mediodorsal thalamus in processing semantic, but not response, conflict. In none of our comparisons did we observe activity in the anterior cingulate cortex (ACC), a finding we ascribe to the use of blocked trial type presentation and one that has implications for theories of ACC function.
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    Response Time Distribution Analysis of Semantic and Response Interference in a Manual Response Stroop Task
    (Hogrefe Publishing, 2019-07-02) Hasshim, Nabil; Downes, Michelle; Bate, Sarah; Parris, Benjamin
    Abstract. Previous analyses of response time distributions have shown that the Stroop effect is observed in the mode (μ) and standard deviation (σ) of the normal part of the distribution, as well as its tail (τ). Specifically, interference related to semantic and response processes has been suggested to specifically affect the mode and tail, respectively. However, only one study in the literature has directly manipulated semantic interference, and none manipulating response interference. The present research aims to address this gap by manipulating both semantic and response interference in a manual response Stroop task, and examining how these components of Stroop interference affect the response time distribution. Ex-Gaussian analysis showed both semantic and response conflict to only affect τ. Analyzing the distribution by rank-ordered response times (Vincentizing) showed converging results as the magnitude of both semantic and response conflict increased with slower response times. Additionally, response conflict appeared earlier on the distribution compared to semantic conflict. These findings further highlight the difficulty in attributing specific psychological processes to different parameters (i.e., μ, σ, and τ). The effect of different response modalities on the makeup of Stroop interference is also discussed.
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    The Role of Contingency and Correlation in the Stroop Task
    (SAGE, 2021-06-30) Hasshim, Nabil; Parris, Benjamin
    Facilitation (faster responses to Congruent trials compared with Neutral trials) in the Stroop task has been a difficult effect for models of cognitive control to explain. The current research investigated the role of word-response contingency, word-colour correlation, and proportion congruency in producing Stroop effects. Contingency and correlation refers to the probability of specific word-response and word-colour pairings that are implicitly learnt while performing the task. Pairs that have a higher probability of occurring are responded to faster, a finding that challenges top-down attention control accounts of Stroop task performance. However, studies that try to experimentally control for contingency and correlation typically do so by increasing the proportion of incongruent trials in the task, which cognitive control accounts posit affects interference control via the top-down biasing of attention. The present research focused on whether facilitation is also affected by contingency and correlation while additionally looking at the effect of proportion congruency. This was done in two experiments that compared the typical design of Stroop task experiments (i.e., having equal proportions of Congruent and Incongruent trials but also contingency and correlational biases) to: (a) a design that had unequal congruency proportions but no contingency or correlation (Experiment 1) and (b) a design where the correlation is biased but proportion congruency and contingency were not (Experiment 2). Results did not support the hypotheses that contingency or correlation affected facilitation. However, interference was almost halved in the alternative design of Experiment 2, demonstrating an effect of contingency learning in typical measures of Stroop interference.
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    Trial type mixing substantially reduces the Response Set Effect in the Stroop task
    (Elsevier, 2017-03-21) Hasshim, Nabil; Parris, Benjamin
    he response set effect refers to the finding that an irrelevant incongruent colour-word produces greater interference when it is one of the response options (referred to as a response set trial), compared to when it is not (a non-response set trial). Despite being a key effect for models of selective attention, the magnitude of the effect varies considerably across studies. We report two within-subjects experiments that tested the hypothesis that presentation format modulates the magnitude of the response set effect. Trial types (e.g. response set, non-response set, neutral) were either presented in separate blocks (pure) or in blocks containing trials from all conditions presented randomly (mixed)). In the first experiment we show that the response set effect is substantially reduced in the mixed block context as a result of a decrease in RTs to response set trials. By demonstrating the modulation of the response set effect under conditions of trial type mixing we present evidence that is difficult for models of the effect based on strategic, top-down biasing of attention to explain. In a second experiment we tested a stimulus-driven account of the response set effect by manipulating the number of colour-words that make up the non-response set of distractors. The results show that the greater the number of non-response set colour concepts, the smaller the response set effect. Alternative accounts of the data and its implications for research debating the automaticity of reading are discussed.