Event Probabilities Have a Different Impact on Early and Late Electroencephalographic Measures Regarded as Metrics of Prediction.

The oddball protocol has been used to study the neural and perceptual consequences of implicit predictions in the human brain. The protocol involves presenting a sequence of identical repeated events that are eventually broken by a novel "oddball" presentation. Oddball presentations have been linked to increased neural responding and to an exaggeration of perceived duration relative to repeated events. Because the number of repeated events in such protocols is circumscribed, as more repeats are encountered, the conditional probability of a further repeat decreases-whereas the conditional probability of an oddball increases. These facts have not been appreciated in many analyses of oddballs; repeats and oddballs have rather been treated as binary event categories. Here, we show that the human brain is sensitive to conditional event probabilities in an active, visual oddball paradigm. P300 responses (a relatively late component of visually evoked potentials measured with EEG) tended to be greater for less likely oddballs and repeats. By contrast, P1 responses (an earlier component) increased for repeats as a goal-relevant target presentation neared, but this effect occurred even when repeat probabilities were held constant, and oddball P1 responses were invariant. We also found that later, more likely oddballs seemed to last longer, and this effect was largely independent of the number of preceding repeats. These findings speak against a repetition suppression account of the temporal oddball effect. Overall, our data highlight an impact of event probability on later, rather than earlier, electroencephalographic measures previously related to predictive processes-and the importance of considering conditional probabilities in sequential presentation paradigms.

The best fitting of three contemporary observer models reveals how participants' strategy influences the window of subjective synchrony.

When experimenters vary the timing between two intersensory events, and participants judge their simultaneity, an inverse-U-shaped psychometric function is obtained. Typically, this simultaneity function is first fitted with a model for each participant separately, before best-fitting parameters are utilized (e.g., compared across conditions) in the second stage of a two-step inferential procedure. Often, simultaneity-function width is interpreted as representing sensitivity to asynchrony, and/or ascribed theoretical equivalence to a window of multisensory temporal binding. Here, we instead fit a single (principled) multilevel model to data from the entire group and across several conditions at once. By asking 20 participants to sometimes be more conservative in their judgments, we demonstrate how the width of the simultaneity function is prone to strategic change and thus questionable as a measure of either sensitivity to asynchrony or multisensory binding. By repeating our analysis with three different models (two implying a decision based directly on subjective asynchrony, and a third deriving this decision from the correlation between filtered responses to sensory inputs) we find that the first model, which hypothesizes, in particular, Gaussian latency noise and difficulty maintaining the stability of decision criteria across trials, is most plausible for these data. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The temporal visual oddball effect is not caused by repetition suppression.

The oddball paradigm is commonly used to investigate human time perception. Trains of identical repeated events ('standards') are presented, only to be interrupted by a different 'oddball' that seems to have a relatively protracted duration. One theoretical account has been that this effect is driven by repetition suppression for repeated standards. The idea is that repeated events seem shorter as they incur a progressively reduced neural response, which is supported by the finding that oddball perceived duration increases linearly with the number of preceding repeated standards. However, typical oddball paradigms confound the probability of oddball presentations with variable numbers of standard repetitions on each trial, allowing people to increasingly anticipate an oddball presentation as more standards are presented. We eliminated this by making participants aware of what fixed number of standards they would encounter before a final test input and tested different numbers of standards in separate experimental sessions. The final event of sequences, the test event, was equally likely to be an oddball or another repeat. We found a positive linear relationship between the number of preceding repeated standards and the perceived duration of oddball test events. However, we also found this for repeat tests events, which speaks against the repetition suppression account of the temporal oddball effect.

On why we lack confidence in some signal-detection-based analyses of confidence.

Signal-detection theory (SDT) is one of the most popular frameworks for analyzing data from studies of human behavior - including investigations of confidence. SDT-based analyses of confidence deliver both standard estimates of sensitivity (d'), and a second estimate informed by high-confidence decisions - meta d'. The extent to which meta d' estimates fall short of d' estimates is regarded as a measure of metacognitive inefficiency, quantifying the contamination of confidence by additional noise. These analyses rely on a key but questionable assumption - that repeated exposures to an input will evoke a normally-shaped distribution of perceptual experiences (the normality assumption). Here we show, via analyses inspired by an experiment and modelling, that when distributions of experience do not conform with the normality assumption, meta d' can be systematically underestimated relative to d'. Our data highlight that SDT-based analyses of confidence do not provide a ground truth measure of human metacognitive inefficiency. We explain why deviance from the normality assumption is especially a problem for some popular SDT-based analyses of confidence, in contrast to other analyses inspired by the SDT framework, which are more robust to violations of the normality assumption.

Spatial attention is not affected by alpha or beta transcranial alternating current stimulation: A registered report.

Using Electroencephalography (EEG) an event-related change in alpha activity has been observed over primary sensory cortices during the allocation of spatial attention. This is most prominent during top-down, or endogenous, attention, and nearly absent in bottom-up, or exogenous orienting. These changes are highly lateralised, such that an increase in alpha power is seen ipsilateral to the attended region of space and a decrease is seen contralaterally. Whether these changes in alpha oscillatory activity are causally related to attentional resources, or to perceptual processes, or are simply epiphenomenal, is unknown. If alpha oscillations are indicative of a causal mechanism whereby attention is allocated to a region of space, it remains an open question as to whether this is driven by ipsilateral increases or contralateral decreases in alpha power. This preregistered report set out to test these questions. To do so, we used transcranial Alternating Current Stimulation (tACS) to modulate alpha activity in the somatosensory cortex whilst measuring performance on established tactile attention paradigms. All participants completed an endogenous and exogenous tactile attention task in three stimulation conditions; alpha, sham and beta. Sham and beta stimulation operated as controls so that any observed effects could be attributed to alpha stimulation specifically. We replicated previous behavioural findings in all stimulation conditions showing a facilitation of cued trials in the endogenous task, and inhibition of return in the exogenous task. However, these were not affected by stimulation manipulations. Using Bayes-factor analysis we show strong support for the null hypotheses - that the manipulation of Alpha by tACS does not cause changes in tactile spatial attention. This well-powered study, conducted over three separate days, is an important contribution to the current debate regarding the efficiency of brain stimulation.

The perceived duration of expected events depends on how the expectation is formed.

Repeated events can seem shortened. It has been suggested that this results from an inverse relationship between predictability and perceived duration, with more predictable events seeming shorter. Some evidence disputes this generalisation, as there are cases where this relationship has been nullified, or even reversed. This study sought to combine different factors that encourage expectation into a single paradigm, to directly compare their effects. We find that when people are asked to declare a prediction (i.e., to predict which colour sequence will ensue), guess-confirming events can seem relatively protracted. This augmented a positive time-order error, with the first of two sequential presentations already seeming protracted. We did not observe a contraction of perceived duration for more probable or for repeated events. Overall, our results are inconsistent with a simple mapping between predictability and perceived duration. Whether the perceived duration of an expected event will seem relatively contracted or expanded seems to be contingent on the causal origin of expectation.

Effects of calorie labelling and contextual factors on hypothetical coffee shop menu choices.

This study examined the effects of calorie labelling and two key contextual factors (reflective motivation and habits) on the calorie content of hypothetical coffee-shop menu choices. In one exploratory (n = 70) and one pre-registered (n = 300) laboratory study (Studies 1 and 2 respectively), participants viewed a hypothetical calorie-labelled or non calorie-labelled menuboard and selected their preferred item(s). Coffee shop drinking habits were measured using the Self-Report Habit Index, and reflective motivation (relating to calorie intake) was assessed with three items asking about watching weight, eating healthily, and reading calorie labels. In Study 2, participants also estimated calories contained in a subset of the menuboard drinks. Results of both studies showed that labelling did not significantly affect the total calorie content of items selected. However, in Study 2, as predicted, there was a trend toward moderation by reflective motivation (p = .056) with less motivated participants showing relatively greater calorie selection when exposed to labelling. Participants with weaker habits took longer to select items (p = .002) but, contrary to predictions, were not more influenced by labelling. Higher reflective motivation was associated with selecting fewer calories (p = .002), correctly recalling the presence/absence of labelling (p = .016) and better estimating calorie content (p < .001). Overall, participants significantly underestimated calories in higher calorie drinks but overestimated calories in lower calorie drinks. The results highlight the importance of contextual factors such as habits and reflective motivation for obesity interventions and are relevant for the UK's introduction of selective mandatory calorie labelling. In some instances, labelling may actually increase intake among those less motivated by health and weight concerns, but further research is needed to substantiate this concern.

Neural prediction errors depend on how an expectation was formed.

When a visual event is unexpected, because it violates a train of repeated events, it excites a greater positive electrical potential at sensors positioned above occipital-parietal human brain regions (the P300). Such events can also seem to have an increased duration relative to repeated (implicitly expected) events. However, recent behavioural evidence suggests that when events are unexpected because they violate a declared prediction-a guess-there is an opposite impact on duration perception. The neural consequences of incorrect declared predictions have not been examined. We replicated the finding whereby repetition violating events elicit a larger P300 response. However, we found that events that violated a declared prediction entrained an opposite pattern of response-a smaller P300. These data suggest that the neural consequences of a violated prediction are not uniform but depend on how the prediction was formed.

Occipital alpha-band brain waves when the eyes are closed are shaped by ongoing visual processes.

One of the seminal findings of cognitive neuroscience is that the power of occipital alpha-band (~ 10 Hz) brain waves is increased when peoples' eyes are closed, rather than open. This has encouraged the view that alpha oscillations are a default dynamic, to which the visual brain returns in the absence of input. Accordingly, we might be unable to increase the power of alpha oscillations when the eyes are closed, above the level that would normally ensue when people close their eyes. Here we report counter evidence. We used electroencephalography (EEG) to record brain activity when people had their eyes open and closed, both before and after they had adapted to radial motion. The increase in alpha power when people closed their eyes was increased by prior adaptation to a broad range of radial motion speeds. This effect was greatest for 10 Hz motion, but robust for other frequencies (and especially 7.5 Hz). This discredits a persistent entrainment of activity at the adaptation frequency as an explanation for our findings. Our data show that the power of occipital alpha-band brain waves can be increased by motion sensitive visual processes that persist when the eyes are closed. Consequently, we suggest that the power of these brain waves is, at least in part, an index of the degree to which visual brain activity is being subjected to inhibition. This is increased when people close their eyes, but can be even further increased by pre-adaptation to radial motion.

Neural-latency noise places limits on human sensitivity to the timing of events.

The brain-time account posits that the physical timing of sensory-evoked neural activity determines the perceived timing of corresponding sensory events. A canonical model formalises this account for tasks such as simultaneity and order judgements: Signals arrive at a decision centre in an order, and at a temporal offset, shaped by neural propagation times. This model assumes that the noise affecting people's temporal judgements is primarily neural-latency noise, i.e. variation in propagation times across trials, but this assumption has received little scrutiny. Here, we recorded EEG alongside simultaneity judgements from 50 participants in response to combinations of visual, auditory and tactile stimuli. Bootstrapping of ERP components was used to estimate neural-latency noise, and simultaneity judgements were modelled to estimate the precision of timing judgements. We obtained the predicted correlation between neural and behavioural measures of latency noise, supporting a fundamental feature of the canonical model of perceived timing.

Visual predictions, neural oscillations and naïve physics.

Prediction is a core function of the human visual system. Contemporary research suggests the brain builds predictive internal models of the world to facilitate interactions with our dynamic environment. Here, we wanted to examine the behavioural and neurological consequences of disrupting a core property of peoples' internal models, using naturalistic stimuli. We had people view videos of basketball and asked them to track the moving ball and predict jump shot outcomes, all while we recorded eye movements and brain activity. To disrupt people's predictive internal models, we inverted footage on half the trials, so dynamics were inconsistent with how movements should be shaped by gravity. When viewing upright videos people were better at predicting shot outcomes, at tracking the ball position, and they had enhanced alpha-band oscillatory activity in occipital brain regions. The advantage for predicting upright shot outcomes scaled with improvements in ball tracking and occipital alpha-band activity. Occipital alpha-band activity has been linked to selective attention and spatially-mapped inhibitions of visual brain activity. We propose that when people have a more accurate predictive model of the environment, they can more easily parse what is relevant, allowing them to better target irrelevant positions for suppression-resulting in both better predictive performance and in neural markers of inhibited information processing.

Post-stroke object affordances: An EEG investigation.

Rehabilitating upper limb function after stroke is a key therapeutic goal. In healthy brains, objects, especially tools, are said to cause automatic motoric 'affordances'; affecting our preparation to handle objects. For example, the N2 event-related potential has been shown to correlate with the functional properties of objects in healthy adults during passive viewing. We posited that such an affordance effect might also be observed in chronic-stage stroke survivors. With either dominant or non-dominant hand forward, we presented three kinds of stimuli in stereoscopic depth; grasp objects affording a power-grip, pinch objects affording a thumb and forefinger precision-grip and an empty desk, affording no action. EEG data from 10 stroke survivors and 15 neurologically healthy subjects were analysed for the N1 and N2 ERP components. Both components revealed differences between the two object stimuli categories and the empty desk for both groups, suggesting the presence of affordance-related motor priming from around 100 to 370 ms after stimulus onset. Hence, we speculate that stroke survivors with loss of upper limb function may benefit from object presentation regimes designed to maximise motor priming when attempting movements with manipulable objects. However, further investigation would be necessary with acute stage patients, especially those diagnosed with apraxia.

Correction to: Predictable events elicit less visual and temporal information uptake in an oddball paradigm.

The Publisher regrets the following production error. The labels for Figures 2, 4, 5, 6, and 7 describe an older version of the figures. The correct figure labels are as follows.

Centroparietal activity mirrors the decision variable when tracking biased and time-varying sensory evidence.

Decision-making is a fundamental human activity requiring explanation at the neurocognitive level. Current theoretical frameworks assume that, during sensory-based decision-making, the stimulus is sampled sequentially. The resulting evidence is accumulated over time as a decision variable until a threshold is reached and a response is initiated. Several neural signals, including the centroparietal positivity (CPP) measured from the human electroencephalogram (EEG), appear to display the accumulation-to-bound profile associated with the decision variable. Here, we evaluate the putative computational role of the CPP as a model-derived accumulation-to-bound signal, focussing on point-by-point correspondence between model predictions and data in order to go beyond simple summary measures like average slope. In two experiments, we explored the CPP under two manipulations (namely non-stationary evidence and probabilistic decision biases) that complement one another by targeting the shape and amplitude of accumulation respectively. We fit sequential sampling models to the behavioural data, and used the resulting parameters to simulate the decision variable, before directly comparing the simulated profile to the CPP waveform. In both experiments, model predictions deviated from our naïve expectations, yet showed similarities with the neurodynamic data, illustrating the importance of a formal modelling approach. The CPP appears to arise from brain processes that implement a decision variable (as formalised in sequential-sampling models) and may therefore inform our understanding of decision-making at both the representational and implementational levels of analysis, but at this point it is uncertain whether a single model can explain how the CPP varies across different kinds of task manipulation.

Neural correlates of subjective timing precision and confidence.

Humans perceptual judgments are imprecise, as repeated exposures to the same physical stimulation (e.g. audio-visual inputs separated by a constant temporal offset) can result in different decisions. Moreover, there can be marked individual differences - precise judges will repeatedly make the same decision about a given input, whereas imprecise judges will make different decisions. The causes are unclear. We examined this using audio-visual (AV) timing and confidence judgments, in conjunction with electroencephalography (EEG) and multivariate pattern classification analyses. One plausible cause of differences in timing precision is that it scales with variance in the dynamics of evoked brain activity. Another possibility is that equally reliable patterns of brain activity are evoked, but there are systematic differences that scale with precision. Trial-by-trial decoding of input timings from brain activity suggested precision differences may not result from variable dynamics. Instead, precision was associated with evoked responses that were exaggerated (more different from baseline) ~300 ms after initial physical stimulations. We suggest excitatory and inhibitory interactions within a winner-take-all neural code for AV timing might exaggerate responses, such that evoked response magnitudes post-stimulation scale with encoding success.

Assessing lower limb position sense in stroke using the gradient discrimination test (GradDT™) and step-height discrimination test (StepDT™): a reliability and validity study.

Purpose: To evaluate the psychometric properties of two novel tests of lower limb position sense.Methods: Our newly developed tests assess the discrimination thresholds of under-foot slope and step height perception using a two alternative forced choice approach. Stroke participants (n = 32) and age matched controls (n = 32) were tested. Inter- and intra-rater reliability and agreement, sensitivity and specificity, discriminant and convergent validity were evaluated.Results: Intra-rater reliability for both variants of the gradient discrimination test was excellent; intraclass correlation coefficients (ICC) =0.91 and 0.89. The step height discrimination test had excellent intra-rater reliability and agreement: ICC =0.95. Inter-rater reliability was also excellent in both tests (ICC= 0.85-0.93). Discriminant validity was demonstrated with significant differences in test performance between stroke and control participants (p < 0.001). Our novel tests did not significantly correlate with the proprioceptive component of the Erasmus modified Nottingham Sensory Assessment. Receiver Operating Characteristic curve analysis indicated both novel tests to have greater sensitivity and specificity than the proprioceptive component of the Erasmus modified Nottingham Sensory Assessment in predicting the presence of self-reported sensory impairments. Functional reach test, 10 meter walk test, centre of pressure measurement and reported falls showed significant and moderate to strong correlations with novel test performance (r = 0.40-0.60); the Erasmus modified Nottingham Sensory Assessment did not.Conclusions: Our novel, functionally oriented tests of lower limb position sense are reliable, valid and feasible for use in an ambulatory chronic stroke and elderly population.Implications for rehabilitationThe GradDT™ and StepDT are two novel tests of lower limb position sense which are reliable and valid in a chronic stroke sample.They offer clinicians and researchers sensitive, accurate and clinically usable measures of lower limb position sense.

Predictable events elicit less visual and temporal information uptake in an oddball paradigm.

In the visual oddball paradigm, surprising inputs can seem expanded in time relative to unsurprising repeated events. A horizontal input embedded in a train of successive vertical inputs can, for instance, seem relatively protracted in time, even if all inputs are presented for an identical duration. It is unclear if this effect results from surprising events becoming apparently protracted, or from repeated events becoming apparently contracted in time. To disambiguate, we used a non-relative duration reproduction task, in which several standards preceded a test stimulus that had to be reproduced. We manipulated the predictability of test content over successive presentations. Overall, our data suggest that predictable stimuli induce a contraction of apparent duration (Experiments 1, 3, and 4). We also examine sensitivity to test content, and find that predictable stimuli elicit less uptake of visual information (Experiments 2 and 3). We discuss these findings in relation to the predictive coding framework.

Information Accrual From the Period Preceding Racket-Ball Contact for Tennis Ground Strokes: Inferences From Stochastic Masking.

Previous research suggests the existence of an expert anticipatory advantage, whereby skilled sportspeople are able to predict an upcoming action by utilizing cues contained in their opponent's body kinematics. This ability is often inferred from "occlusion" experiments: information is systematically removed from first-person videos of an opponent, for example, by stopping a tennis video at the point of racket-ball contact, yet performance, such as discrimination of shot direction, remains above chance. In this study, we assessed the expert anticipatory advantage for tennis ground strokes via a modified approach, known as "bubbles," in which information is randomly removed from videos in each trial. The bubbles profile is then weighted by trial outcome (i.e., a correct vs. incorrect discrimination) and combined across trials into a classification array, revealing the potential cues informing the decision. In two experiments (both with N = 34 skilled tennis players) we utilized either temporal or spatial bubbles, applying them to videos running from 0.8 to 0 s before the point of racket-ball contact (cf. Jalali et al., 2018). Results from the spatial experiment were somewhat suggestive of accrual from the torso region of the body, but were not compelling. Results from the temporal experiment, on the other hand, were clear: information was accrued mainly during the period immediately prior to racket-ball contact. This result is broadly consistent with prior work using nonstochastic approaches to video manipulation, and cannot be an artifact of temporal smear from information accrued after racket-ball contact, because no such information was present.

Assessing Plantar Sensation in the Foot Using the Foot Roughness Discrimination Test (FoRDT): A Reliability and Validity Study in Stroke.

BACKGROUND: The plantar foot represents a sensory dynamometric map and is essential for balance and gait control. Sensory impairments are common, yet often difficult to quantify in neurological conditions, particularly stroke. A functionally oriented and quantifiable assessment, the Foot Roughness Discrimination Test (FoRDT), was developed to address these shortcomings. OBJECTIVE: To evaluate inter- and intrarater reliability, convergent and discriminant validity of the FoRDT. DESIGN: Test-retest design. SETTING: Hospital outpatient. PARTICIPANTS: Thirty-two people with stroke (mean age 70 years) at least 3 months after stroke, and 32 healthy, age-matched controls (mean age 70). MAIN OUTCOME MEASURES: Roughness discrimination thresholds were quantified utilizing acrylic foot plates, laser cut to produce graded spatial gratings. Stroke participants were tested on three occasions, and by two different raters. Inter- and intrarater reliability and agreement were evaluated with Intraclass Correlation Coefficients and Bland-Altman plots. Convergent validity was evaluated through Spearman rank correlation coefficients (rho) between the FoRDT and the Erasmus modified Nottingham Sensory Assessment (EmNSA). RESULTS: Intra- and interrater reliability and agreement were excellent (ICC =0.86 [95% CI 0.72-0.92] and 0.90 [95% CI 0.76-0.96]). Discriminant validity was demonstrated through significant differences in FoRDT between stroke and control participants (P < .001). Stroke fallers had statistically significant higher FoRDT scores compared with nonfallers (P = .01). Convergent validity was demonstrated through significant and strong correlations (rho) with the Erasmus MC Nottingham Sensory Assessment (r = .69, P < .01). Receiver operator characteristic curve analysis indicated the novel test to have excellent sensitivity and specificity in predicting the presence of self-reported sensory impairments. Functional Reach test significantly correlated with FoRDT (r = .62, P < .01) whereas measures of postural sway and gait speed did not (r = .16-.26, P > .05). CONCLUSIONS: This simple and functionally oriented test of plantar sensation is reliable, valid, and clinically feasible for use in an ambulatory, chronic stroke and older population. It offers clinicians and researchers a sensitive and robust sensory measure and may further support the evaluation of rehabilitation targeting foot sensation. LEVEL OF EVIDENCE: III.

Financial interests of patient organisations contributing to technology assessment at England's National Institute for Health and Care Excellence: policy review.

OBJECTIVE: To investigate the prevalence of financial interests among patient organisations contributing to health technology assessment at the National Institute for Health and Care Excellence (NICE) in England and the extent to which NICE's disclosure policy ensures that decision making committees are aware of these interests. DESIGN: Policy review using accounts, annual reports, and websites of patient organisations; payments declared by pharmaceutical manufacturers on their websites and a centralised database (Disclosure UK); declarations of interests by nominated representatives of patient organisations; and responses from patient organisations. SETTING: Appraisals of medicines and treatments (technologies) for use in the English and Welsh National Health Service. PARTICIPANTS: 53 patient organisations contributing to 41 NICE technology appraisals published in 2015 and 2016, with 117 separate occasions that a patient organisation contributed to the appraisal of a technology. MAIN OUTCOME MEASURES: Prevalence of specific interests (that is, funding from manufacturer(s) of a technology under appraisal or competitor products); proportion of specific interests of which NICE's decision making committees were aware; proportion of unknown specific interests for which disclosure was not required by NICE's policy RESULTS: 38/53 (72%) patient organisations had accepted funding from the manufacturer(s) of a technology or a competitor product in the same year that they had contributed to the appraisal of that technology or the previous year. Specific interests were present on 92/117 (79%) occasions that patient organisations contributed to appraisals in 2015 and 2016. NICE's decision making committees were aware of less than a quarter of specific interests (30/144; 21%). For nearly two thirds of the specific interests not known to committees (71/114; 62%), disclosure by patient organisations was not required by NICE's policy. CONCLUSIONS: Financial interests are highly prevalent among patient organisations contributing to health technology assessment. NICE should review its disclosure policy to ensure that decision making committees are aware of all relevant interests.