Melbourne School of Psychological Sciences - Research Publications

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    An Extended Commentary on Post-Publication Peer Review In Organizational Neuroscience
    Prochilo, GA ; Louis, WR ; Bode, S ; Zacher, H ; Molenberghs, P ( 2018-10-03)
    While considerable progress has been made in organizational neuroscience over the past decade, we argue that critical evaluations of published empirical works are not being conducted carefully and consistently. In this extended commentary we take as an example Waldman and colleagues (2017): a major review work that evaluates the state-of-the-art of organizational neuroscience. In what should be an evaluation of the field’s empirical work, the authors uncritically summarize a series of studies that: (1) provide insufficient transparency to be clearly understood, evaluated, or replicated, and/or (2) which misuse inferential tests that lead to misleading conclusions, among other concerns. These concerns have been ignored across multiple major reviews and citing articles. We therefore provide a post-publication review (in two parts) of one-third of all studies evaluated in Waldman and colleague’s major review work. In Part I, we systematically evaluate the field’s two seminal works with respect to their methods, analytic strategy, results, and interpretation of findings. And in Part II, we provide focused reviews of secondary works that each center on a specific concern we suggest should be a point of discussion as the field moves forward. In doing so, we identify a series of practices we recommend will improve the state of the literature. This includes: (1) evaluating the transparency and completeness of an empirical article before accepting its claims, (2) becoming familiar with common misuses or misconceptions of statistical testing, and (3) interpreting results with an explicit reference to effect size magnitude, precision, and accuracy, among other recommendations. We suggest that adopting these practices will motivate the development of a more replicable, reliable, and trustworthy field of organizational neuroscience moving forward. Note: this manuscript has been peer reviewed and is published in Meta-Psychology. Please cite as: Prochilo, G. A., Louis, W. R., Bode, S., Zacher, H., & Molenberghs, P. (2019). An Extended Commentary on Post-publication Peer Review in Organizational Neuroscience. Meta-Psychology, 3. https://doi.org/10.15626/MP.2018.935 |
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    Caloric Primary Rewards Systematically Alter Time Perception
    Fung, BJ ; Murawski, C ; Bode, S ( 2017-04-26)
    Human time perception can be influenced by contextual factors, such as the presence of reward. Yet, the exact nature of the relationship between time perception and reward has not been conclusively characterized. We implemented a novel experimental paradigm to measure estimations of time across a range of suprasecond intervals, during the anticipation and after the consumption of fruit juice, a physiologically relevant primary reward. We show that average time estimations were systematically affected by the consumption of reward, but not by the anticipation of reward. Compared with baseline estimations of time, reward consumption was associated with subsequent overproductions of time, and this effect increased for larger magnitudes of reward. Additional experiments demonstrated that the effect of consumption did not extend to a secondary reward (money), a tasteless, noncaloric primary reward (water), or a sweet, noncaloric reward (aspartame). However, a tasteless caloric reward (maltodexrin) did induce overproductions of time, although this effect did not scale with reward magnitude. These results suggest that the consumption of caloric primary rewards can alter time perception, which may be a psychophysiological mechanism by which organisms regulate homeostatic balance.
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    Tracking dynamic adjustments to decision making and performance monitoring processes in conflict tasks
    Feuerriegel, D ; Jiwa, M ; Turner, WF ; Andrejević, M ; Hester, R ; Bode, S ( 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.
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    Visual mismatch responses index surprise signalling but not expectation suppression
    Feuerriegel, D ; Yook, J ; Quek, GL ; Hogendoorn, H ; Bode, S ( 2020-06-24)
    Abstract The ability to distinguish between commonplace and unusual sensory events is critical for efficient learning and adaptive behaviour. This has been investigated using oddball designs in which sequences of often-appearing (i.e. expected) stimuli are interspersed with rare (i.e. surprising) deviants. Resulting differences in electrophysiological responses following surprising compared to expected stimuli are known as visual mismatch responses (VMRs). VMRs are thought to index co-occurring contributions of stimulus repetition effects, expectation suppression (that occurs when one’s expectations are fulfilled), and expectation violation (i.e. surprise) responses; however, these different effects have been conflated in existing oddball designs. To better isolate and quantify effects of expectation suppression and surprise, we adapted an oddball design based on Fast Periodic Visual Stimulation (FPVS) that controls for stimulus repetition effects. We recorded electroencephalography (EEG) while participants (N=48) viewed stimulation sequences in which a single face identity was periodically presented at 6 Hz. Critically, one of two different face identities (termed oddballs) appeared as every 7th image throughout the sequence. The presentation probabilities of each oddball image within a sequence varied between 10-90%, such that participants could form expectations about which oddball face identity was more likely to appear within each sequence. We also included ‘expectation neutral’ 50% probability sequences, whereby consistently biased expectations would not be formed for either oddball face identity. We found that VMRs indexed surprise responses, and effects of expectation suppression were absent. That is, ERPs were more negative-going at occipitoparietal electrodes for surprising compared to neutral oddballs, but did not differ between expected and neutral oddballs. Surprising oddball-evoked ERPs were also highly similar across the 10-40% appearance probability conditions. Our findings indicate that VMRs which are not accounted for by repetition effects are best described as an all-or-none surprise response, rather than a minimisation of prediction error responses associated with expectation suppression. Highlights -We used a recently-developed oddball design that controls for repetition effects -We found effects of surprise but not expectation suppression on ERPs -Surprise responses did not vary by stimulus appearance probability
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    Perceptual decision confidence is sensitive to forgone physical effort expenditure
    Turner, W ; Angdias, R ; Feuerriegel, D ; Chong, T ; Hester, R ; Bode, S ( 2020-06-10)
    Contemporary theoretical accounts of metacognition propose that action-related information is used in the computation of perceptual decision confidence. We investigated whether the amount of expended physical effort, or the ‘motoric sunk cost’ of a decision, influences perceptual decision confidence judgements in humans. In particular, we examined whether people feel more confident in decisions which required more effort to report. Forty-two participants performed a luminance discrimination task that involved identifying which of two flickering grayscale squares was brightest. Participants reported their choice by squeezing hand-held dynamometers. Across trials, the effort required to report a decision was varied across three levels (low, medium, high). Critically, participants were only aware of the required effort level on each trial once they had initiated their motor response, meaning that the varying effort requirements could not influence their initial decisions. Following each decision, participants rated their confidence in their choice. We found that participants were more confident in decisions that required greater effort to report. This suggests that humans are sensitive to motoric sunk costs and supports contemporary models of metacognition in which actions inform the computation of decision confidence.
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    The relationship between response dynamics and the formation of confidence varies across the lifespan
    Overhoff, H ; Ko, YH ; Fink, GR ; Stahl, J ; Weiss, PH ; Bode, S ; Niessen, E ( 2022-06-16)
    Accurate metacognitive judgements, such as forming a confidence judgement, are crucial for goaldirected behaviour but decline with older age. Besides changes in the sensory processing of stimulus features, there might also be changes in the motoric aspects of giving responses that account for age-related changes in confidence. In order to assess the association between confidence and response parameters across the adult lifespan, we measured response times and peak forces in a four-choice flanker task with subsequent confidence judgements. In 65 healthy adults from 20 to 76 years of age, we showed divergent associations of each measure with confidence, depending on decision accuracy. Participants indicated higher confidence after faster responses in correct but not incorrect trials. They also indicated higher confidence after less forceful responses in errors but not in correct trials. Notably, these associations were age-dependent as the relationship between confidence and response time was more pronounced in older participants, while the relationship between confidence and response force decayed with age. Our results add to the notion that confidence is related to response parameters and demonstrate noteworthy changes in the observed associations across the adult lifespan. These changes potentially constitute an expression of general age-related deficits in performance monitoring or, alternatively, index a failing mechanism in the computation of confidence in older adults.
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    Neural correlates of metacognition across the adult lifespan
    Overhoff, H ; Ko, YH ; Feuerriegel, D ; Fink, G ; Stahl, J ; Weiss, P ; Bode, S ; Niessen, E ( 2021)
    Metacognitive accuracy describes the degree of overlap between the subjective perception of one’s decision accuracy (i.e., confidence) and objectively observed performance. With older age, the need for accurate metacognitive evaluation increases; however, error detection rates typically decrease. We investigated the effect of ageing on metacognitive accuracy using event-related potentials (ERPs) reflecting error detection and confidence: the error/correct negativity (N e/c ) and the error/correct positivity (P e/c ). Sixty-five healthy adults (20 to 76 years) completed a complex perceptual task and provided confidence ratings. We found that metacognitive accuracy declined with age beyond the expected decline in task performance, while the adaptive adjustment of behaviour was well preserved. P e/c amplitudes varied by confidence rating, but they did not mirror the reduction in metacognitive accuracy. N e/c amplitudes decreased with age except for high confidence correct responses. The results suggest that age-related difficulties in metacognitive evaluation could be related to an impaired integration of decision accuracy and confidence information processing. Ultimately, training the metacognitive evaluation of fundamental decisions in older adults might constitute a promising endeavour.
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    Response time modelling reveals evidence for multiple, distinct sources of moral decision caution
    Andrejević, M ; White, JP ; Feuerriegel, D ; Laham, S ; Bode, S ( 2021-01-28)
    People are often cautious in delivering moral judgments of others’ behaviours, as falsely accusing others of wrongdoing can be costly for social relationships. Caution might further be present when making judgements in information-dynamic environments, as contextual updates can change our minds. This study investigated the processes with which moral valence and context expectancy drive caution in moral judgements. Across two experiments, participants (N = 122) made moral judgements of others’ sharing actions. Prior to judging, participants were informed whether contextual information regarding the deservingness of the recipient would follow. We found that participants slowed their moral judgements when judging negatively valenced actions and when expecting contextual updates. Using a diffusion decision model framework, these changes were explained by shifts in drift rate and decision bias (valence) and boundary setting (context), respectively. These findings demonstrate how moral decision caution can be decomposed into distinct aspects of the unfolding decision process.
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    An initial ‘snapshot’ of sensory information biases the likelihood and speed of subsequent changes of mind
    Turner, W ; Feuerriegel, D ; Hester, R ; Bode, S ( 2020-11-27)
    Abstract: We often need to rapidly change our mind about perceptual decisions in order to account for new information and correct mistakes. One fundamental, unresolved question is whether information processed prior to a decision being made (‘pre-decisional information’) has any influence on the likelihood and speed with which that decision is reversed. We investigated this using a luminance discrimination task in which participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli briefly remained on screen, and participants could change their response. Using psychophysical reverse correlation, we examined how moment-to-moment fluctuations in stimulus luminance affected participants’ decisions. This revealed that the strength of even the very earliest (pre-decisional) evidence was associated with the likelihood and speed of later changes of mind. To account for this effect, we propose an extended diffusion model in which an initial ‘snapshot’ of sensory information biases ongoing evidence accumulation. Author Summary: To avoid harm in an ever-changing world we need to be able to rapidly change our minds about our decisions. For example, imagine being unable to overrule a decision to run across a street when you realise a speeding car is approaching. In this study, we examined the information processing dynamics which underlie perceptual judgements and changes of mind. By reverse correlating participants decisions with the moment-to-moment sensory evidence they received, we show that the very earliest information, processed prior to an initial decision being made, can have a lasting influence over the speed and likelihood of subsequent changes of mind. To account for this, we develop a model of perceptual decisions in which initial sensory evidence exerts a lasting bias over later evidence processing. When fit to participants’ behavioural responses alone, this model predicted their observed information usage patterns. This suggests that an initial ‘snapshot’ of sensory information may influence the ongoing dynamics of the perceptual decision process, thus influencing the speed and likelihood of decision reversals.
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    Decoding explicit and implicit representations of health and taste attributes of foods in the human brain
    Schubert, E ; Rosenblatt, D ; Eliby, D ; Kashima, Y ; Hogendoorn, H ; Bode, S ( 2021)
    Obesity has become a significant problem word-wide and is strongly linked to poor food choices. Even in healthy individuals, taste perceptions often drive dietary decisions more strongly than healthiness. This study tested whether health and taste representations can be directly decoded from brain activity, both when explicitly considered, and when implicitly processed for decision-making. We used multivariate support vector regression for event-related potentials (as measured by the electroencephalogram) occurring in the first second of food cue processing to predict ratings of tastiness and healthiness. In Experiment 1, 37 healthy participants viewed images of various foods and explicitly rated their tastiness and healthiness, whereas in Experiment 2, 89 healthy participants indicated their desire to consume snack foods, with no explicit instruction to consider tastiness or healthiness. In Experiment 1 both attributes could be decoded, with taste information being available earlier than health. In Experiment 2, both dimensions were also decodable, and their significant decoding preceded the decoding of decisions (i.e., desire to consume the food). However, in Experiment 2, health representations were decodable earlier than taste representations. These results suggest that health information is activated in the brain during the early stages of dietary decisions, which is promising for designing obesity interventions aimed at quickly activating health awareness.