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result(s) for
"Travers, Eoin"
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Do readiness potentials happen all the time?
by
Khalighinejad, Nima
,
Travers, Eoin
,
Schurger, Aaron
in
Adult
,
Algorithms
,
Cerebral Cortex - physiology
2020
The Readiness Potential (RP) is a slow negative EEG potential found in the seconds preceding voluntary actions. Here, we explore whether the RP is found only at this time, or if it also occurs when no action is produced. Recent theories suggest the RP reflects the average of accumulated stochastic fluctuations in neural activity, rather than a specific signal related to self-initiated action: RP-like events should then be widely present, even in the absence of actions. We investigated this hypothesis by searching for RP-like events in background EEG of an appropriate dataset for which the action-locked EEG had previously been analysed to test other hypotheses [Khalighinejad, N., Brann, E., Dorgham, A., Haggard, P. Dissociating cognitive and motoric precursors of human self-initiated action. Journal of Cognitive Neuroscience. 2019, 1-14]. We used the actual mean RP as a template, and searched the entire epoch for similar neural signals, using similarity metrics that capture the temporal or spatial properties of the RP. Most EEG epochs contained a number of events that were similar to the true RP, but did not lead directly to any voluntary action. However, these RP-like events were equally common in epochs that eventually terminated in voluntary actions as in those where voluntary actions were not permitted. Events matching the temporal profile of the RP were also a poor match for the spatial profile, and vice versa. We conclude that these events are false positives, and do not reflect the same mechanism as the RP itself. Finally, applying the same template-search algorithm to simulated EEG data synthesized from different noise distributions showed that RP-like events will occur in any dataset containing the 1⁄f noise ubiquitous in EEG recordings. To summarise, we found no evidence of genuinely RP-like events at any time other than immediately prior to self-initiated actions. Our findings do not support a purely stochastic model of RP generation, and suggest that the RP may be a specific precursor of self-initiated voluntary actions.
•Readiness Potential-like events occur in background EEG long before voluntary actions.•However, these events occur to the same degree in control data.•They also occur to the same degree in simulated spectrally-matched noise.•EEG more than 2 s before where voluntary actions does not differ from control data.
Journal Article
Validating the Unmind Index as a measure of mental health and wellbeing among adults in USA, Australia, and New Zealand
2023
The Unmind Index is a 26-item, 7-subscale measure of mental health and wellbeing designed for use on the Unmind digital workplace mental health platform. The Unmind Index was developed and validated in the UK but is used internationally. This paper reports further psychometric validation of this measure for use in USA, Australia, and New Zealand (ANZ). Study 1 establishes the factor structure, reliability, convergent and discriminant validity, and measurement invariance by age and gender of the Unmind Index separately for USA and for ANZ. Study 2 further demonstrates measurement invariance across locations, and establishes benchmark scores by location, age, and gender. We conclude that the Unmind Index is valid and reliable as a measure of mental health and wellbeing in these locations.
Journal Article
Leadership and tempo perturbation affect coordination in medium-sized groups
2021
In marching bands, sports, dance and virtually all human group behaviour, we coordinate our actions with others. Coordinating actions in time and space can act as a social glue, facilitating bonding among people. However, much of our understanding about coordination dynamics is based on research into dyadic interactions. Little is known about the nature of the sensorimotor underpinnings and social bonding outcomes of coordination in medium-sized groups—the type of groups, in which most everyday teamwork takes place. In this study, we explored how the presence of a leader and an unexpected perturbation influence coordination and cohesion in a naturalistic setting. In groups of seven, participants were instructed to walk in time to an auditory pacing signal. We found that the presence of a reliable leader enhanced coordination with the target tempo, which was disrupted when the leader abruptly changed their movement tempo. This effect was not observed on coordination with the group members. Moreover, participants’ perceptions of being a follower and group cooperativeness increased in the presence of a leader. This study extends our knowledge about coordination beyond previous work on dyads. We discuss our results in light of sensorimotor coupling and social cohesion theories of coordination in groups.
Journal Article
Confidence is higher in touch than in vision in cases of perceptual ambiguity
2018
The inclination to touch objects that we can see is a surprising behaviour, given that vision often supplies relevant and sufficiently accurate sensory evidence. Here we suggest that this ‘fact-checking’ phenomenon could be explained if touch provides a higher level of perceptual certainty than vision. Testing this hypothesis, observers explored inverted T-shaped stimuli eliciting the Vertical-horizontal illusion in vision and touch, which included clear-cut and ambiguous cases. In separate blocks, observers judged whether the vertical bar was shorter or longer than the horizontal bar and rated the confidence in their judgments. Decisions reached by vision were objectively more accurate than those reached by touch with higher overall confidence ratings. However, while confidence was higher for vision rather than for touch in clear-cut cases, observers were more confident in touch when the stimuli were ambiguous. This relative bias as a function of ambiguity qualifies the view that confidence tracks objective accuracy and uses a comparable mapping across sensory modalities. Employing a perceptual illusion, our method disentangles objective and subjective accuracy showing how the latter is tracked by confidence and point towards possible origins for ‘fact checking’ by touch.
Journal Article
Evidence accumulation under uncertainty - a neural marker of emerging choice and urgency
by
Travers, Eoin
,
Haggard, Patrick
,
Parés-Pujolràs, Elisabeth
in
Action
,
Computer applications
,
Decision
2021
•The classic P3 tracks the evolution of an internal category-specific decision variable in humans.•The amplitude of the P3 evoked by competing evidence items predicts choice on a single-trial level.•The decision variable is modulated by an internal time-dependant urgency signal.•This urgency signal was stronger in conditions with lower rates of evidence.•Primacy and recency effects can be accounted for by context-dependant urgency modulations.
To interact meaningfully with its environment, an agent must integrate external information with its own internal states. However, information about the environment is often noisy. In this study, we identify a neural correlate that tracks how asymmetries between competing alternatives evolve over the course of a decision. In our task participants had to monitor a stream of discrete visual stimuli over time and decide whether or not to act, on the basis of either strong or ambiguous evidence. We found that the classic P3 event-related potential evoked by sequential evidence items tracked decision-making processes and predicted participants’ categorical choices on a single trial level, both when evidence was strong and when it was ambiguous. The P3 amplitudes in response to evidence supporting the eventually selected option increased over trial time as decisions evolved, being maximally different from the P3 amplitudes evoked by competing evidence at the time of decision. Computational modelling showed that both the neural dynamics and behavioural primacy and recency effects can be explained by a combination of (a) competition between mutually inhibiting accumulators for the two categorical choice outcomes, and (b) a context-dependant urgency signal. In conditions where evidence was presented at a low rate, urgency increased faster than in conditions when evidence was very frequent. We also found that the readiness potential, a classic marker of endogenously initiated actions, was observed preceding movements in all conditions - even when those were strongly driven by external evidence.
Journal Article
Validating the Unmind Index as a measure of mental health and wellbeing among adults in USA, Australia, and New Zealand
2023
Validates the psychometric properties of the Unmind Index, a 26-item, 7-subscale measure of mental health and wellbeing designed for use on the Unmind digital workplace mental health platform, in the USA, Australia, and New Zealand. Explores potential differences in the hierarchical structure of mental health and wellbeing (MHWB) across these countries and the United Kingdom. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Journal Article
Is This Chatbot Safe and Evidence-Based? A Call for the Critical Evaluation of Generative AI Mental Health Chatbots
by
Mullan, Phil
,
Travers, Eoin
,
Parks, Acacia
in
AI-Powered Therapy Bots and Virtual Companions in Digital Mental Health
,
Chatbots
,
Chatbots and Conversational Agents
2025
The proliferation of artificial intelligence (AI)–based mental health chatbots, such as those on platforms like OpenAI’s GPT Store and Character. AI, raises issues of safety, effectiveness, and ethical use; they also raise an opportunity for patients and consumers to ensure AI tools clearly communicate how they meet their needs. While many of these tools claim to offer therapeutic advice, their unregulated status and lack of systematic evaluation create risks for users, particularly vulnerable individuals. This viewpoint article highlights the urgent need for a standardized framework to assess and demonstrate the safety, ethics, and evidence basis of AI chatbots used in mental health contexts. Drawing on clinical expertise, research, co-design experience, and the World Health Organization’s guidance, the authors propose key evaluation criteria: adherence to ethical principles, evidence-based responses, conversational skills, safety protocols, and accessibility. Implementation challenges, including setting output criteria without one “right answer,” evaluating multiturn conversations, and involving experts for oversight at scale, are explored. The authors advocate for greater consumer engagement in chatbot evaluation to ensure that these tools address users’ needs effectively and responsibly, emphasizing the ethical obligation of developers to prioritize safety and a strong base in empirical evidence.
Journal Article
A New Digital Assessment of Mental Health and Well-being in the Workplace: Development and Validation of the Unmind Index
2022
Unmind is a workplace, digital, mental health platform with tools to help users track, maintain, and improve their mental health and well-being (MHWB). Psychological measurement plays a key role on this platform, providing users with insights on their current MHWB, the ability to track it over time, and personalized recommendations, while providing employers with aggregate information about the MHWB of their workforce.
Due to the limitations of existing measures for this purpose, we aimed to develop and validate a novel well-being index for digital use, to capture symptoms of common mental health problems and key aspects of positive well-being.
In Study 1A, questionnaire items were generated by clinicians and screened for face validity. In Study 1B, these items were presented to a large sample (n=1104) of UK adults, and exploratory factor analysis was used to reduce the item pool and identify coherent subscales. In Study 2, the final measure was presented to a new nationally representative UK sample (n=976), along with a battery of existing measures, with 238 participants retaking the Umind Index after 1 week. The factor structure and measurement invariance of the Unmind Index was evaluated using confirmatory factor analysis, convergent and discriminant validity by estimating correlations with existing measures, and reliability by examining internal consistency and test-retest intraclass correlations.
Studies 1A and 1B yielded a 26-item measure with 7 subscales: Calmness, Connection, Coping, Happiness, Health, Fulfilment, and Sleep. Study 2 showed that the Unmind Index is fitted well by a second-order factor structure, where the 7 subscales all load onto an overall MHWB factor, and established measurement invariance by age and gender. Subscale and total scores correlate well with existing mental health measures and generally diverge from personality measures. Reliability was good or excellent across all subscales.
The Unmind Index is a robust measure of MHWB that can help to identify target areas for intervention in nonclinical users of a mental health app. We argue that there is value in measuring mental ill health and mental well-being together, rather than treating them as separate constructs.
Journal Article
Aesthetic experience enhances first-person spatial representation
2022
Episodic autobiographical memories are characterized by a spatial context and an affective component. But how do affective and spatial aspects interact? Does affect modulate the way we encode the spatial context of events? We investigated how one element of affect, namely aesthetic liking, modulates memory for location, in three online experiments (n = 124, 79, and 80). Participants visited a professionally curated virtual art exhibition. They then relocated previously viewed artworks on the museum map and reported how much they liked them. Across all experiments, liking an artwork was associated with increased ability to recall the wall on which it was hung. The effect was not explained by viewing time and appeared to modulate recognition speed. The liking-wall memory effect remained when participants attended to abstractness, rather than liking, and when testing occurred 24 h after the museum visit. Liking also modulated memory for the room where a work of art was hung, but this effect primarily involved reduced room memory for disliked artworks. Further, the liking-wall memory effect remained after controlling for effects of room memory. Recalling the wall requires recalling one’s facing direction, so our findings suggest that positive aesthetic experiences enhance first-person spatial representations. More generally, a first-person component of positive affect transfers to wider spatial representation and facilitates the encoding of locations in a subject-centered reference frame. Affect and spatial representations are therefore important, and linked, elements of sentience and subjectivity. Memories of aesthetic experiences are also spatial memories of how we encountered a work of art. This linkage may have implications for museum design.
Journal Article
The Readiness Potential reflects the internal source of action, rather than decision uncertainty
2020
Voluntary actions are preceded by a Readiness Potential (RP), a slow EEG component generated in medial frontal cortical areas. The RP is classically thought to be specific to internally-driven decisions to act, and to reflect post-decision motor preparation. Recent work suggests instead that it may reflect noise or conflict during the decision itself, with internally-driven decisions tending to be more random, more conflictual and thus more uncertain than externally-driven actions. To contrast accounts based on endogenicity with accounts based on uncertainty, we recorded EEG in a task where participants decided to act or withhold action to accept or reject visually-presented gambles, and used multivariate methods to extract an RP-like component.. We found no difference in amplitude of this component between actions driven by strong versus weak evidence, suggesting that the RP may not reflect uncertainty. In contrast, the same RP-like component showed higher amplitudes prior to actions performed without any external evidence (guesses) than for actions performed in response to equivocal, conflicting evidence. This supports the view that the RP reflects the internal source of action, rather than decision uncertainty.
The EEG Readiness Potential (RP) seen prior to self-initiated actions is often taken as a neural marker of volition (Shibasaki & Hallett, 2006). It has been argued that the RP may instead reflect conflict and uncertainty in the decisions leading up to these actions, raising questions about decades of previous findings. We directly tested these explanations by asking participants to decide whether to act or not in a gambling task, while manipulating both uncertainty and the source of the information (internal or external) guiding the decision. Only the source of information affected the presence of the RP. Therefore, the RP remains a marker of internally-generated voluntary action, not a marker of uncertainty.