Lewis Forder

Can mindfulness and acceptance be learnt by self-help?: A systematic review and meta-analysis of mindfulness and acceptance-based self-help interventions

There is growing evidence that mindfulness and acceptance-based interventions have positive consequences for psychological and physical health. The most well-established of these interventions typically involve relatively large resource commitments, in terms of both the provider and participant. A number of recent studies have begun to explore whether the benefits of such interventions can be generalised to less intensive methods. Methods include pure and guided self-help utilising resources such as books and workbooks, computer programmes and applications and audio-visual materials. This paper presents a systematic review and meta-analysis of studies that have evaluated the effectiveness and acceptability of low-intensity interventions including mindfulness and acceptance-based components. Fifteen RCTs (7 ACT-based, 4 mindfulness-based and 4 multi-component interventions including elements of mindfulness and/or acceptance) were identified and reviewed. Interventions that included mindfulness and/or acceptance-based components produced significant benefits in comparison to control conditions on measures of mindfulness/acceptance, depression and anxiety with small to medium effect sizes. Engagement with the self-help interventions varied but on average two-thirds of participants completed post-intervention measures. Emerging research into low-intensity mindfulness and acceptance-based interventions is hopeful. Recommendations for research and practice are presented.

Color categories only affect post-perceptual processes when same- and different-category colors are equally discriminable

Prior claims that color categories affect color perception are confounded by inequalities in the color space used to equate same- and different-category colors. Here, we equate same- and different-category colors in the number of just-noticeable differences, and measure event-related potentials (ERPs) to these colors on a visual oddball task to establish if color categories affect perceptual or post-perceptual stages of processing. Category effects were found from 200 ms after color presentation, only in ERP components that reflect post-perceptual processes (e.g., N2, P3). The findings suggest that color categories affect post-perceptual processing, but do not affect the perceptual representation of color.

A neural signature of the unique hues

Since at least the 17th century there has been the idea that there are four simple and perceptually pure “unique” hues: red, yellow, green, and blue, and that all other hues are perceived as mixtures of these four hues. However, sustained scientific investigation has not yet provided solid evidence for a neural representation that separates the unique hues from other colors. We measured event-related potentials elicited from unique hues and the ‘intermediate’ hues in between them. We find a neural signature of the unique hues 230 ms after stimulus onset at a post-perceptual stage of visual processing. Specifically, the posterior P2 component over the parieto-occipital lobe peaked significantly earlier for the unique than for the intermediate hues (Z = −2.9, p = 0.004). Having identified a neural marker for unique hues, fundamental questions about the contribution of neural hardwiring, language and environment to the unique hues can now be addressed.

Colour categories are reflected in sensory stages of colour perception when stimulus issues are resolved

Debate exists about the time course of the effect of colour categories on visual processing. We investigated the effect of colour categories for two groups who differed in whether they categorised a blue-green boundary colour as the same- or different-category to a reliably-named blue colour and a reliably-named green colour. Colour differences were equated in just-noticeable differences to be equally discriminable. We analysed event-related potentials for these colours elicited on a passive visual oddball task and investigated the time course of categorical effects on colour processing. Support for category effects was found 100 ms after stimulus onset, and over frontal sites around 250 ms, suggesting that colour naming affects both early sensory and later stages of chromatic processing.

Colour terms affect detection of colour and colour-associated objects suppressed from visual awareness

The idea that language can affect how we see the world continues to create controversy. A potentially important study in this field has shown that when an object is suppressed from visual awareness using continuous flash suppression (a form of binocular rivalry), detection of the object is differently affected by a preceding word prime depending on whether the prime matches or does not match the object. This may suggest that language can affect early stages of vision. We replicated this paradigm and further investigated whether colour terms likewise influence the detection of colours or colour-associated object images suppressed from visual awareness by continuous flash suppression. This method presents rapidly changing visual noise to one eye while the target stimulus is presented to the other. It has been shown to delay conscious perception of a target for up to several minutes. In Experiment 1 we presented greyscale photos of objects. They were either preceded by a congruent object label, an incongruent label, or white noise. Detection sensitivity (d’) and hit rates were significantly poorer for suppressed objects preceded by an incongruent label compared to a congruent label or noise. In Experiment 2, targets were coloured discs preceded by a colour term. Detection sensitivity was significantly worse for suppressed colour patches preceded by an incongruent colour term as compared to a congruent term or white noise. In Experiment 3 targets were suppressed greyscale object images preceded by an auditory presentation of a colour term. On congruent trials the colour term matched the object’s stereotypical colour and on incongruent trials the colour term mismatched. Detection sensitivity was significantly poorer on incongruent trials than congruent trials. Overall, these findings suggest that colour terms affect awareness of coloured stimuli and colour- associated objects, and provide new evidence for language-perception interaction in the brain.

Behavioural and neural modulation of win-stay but not lose-shift strategies as a function of outcome value in Rock, Paper, Scissors

Competitive environments in which individuals compete for mutually-exclusive outcomes require rational decision making in order to maximize gains but often result in poor quality heuristics. Reasons for the greater reliance on lose-shift relative to win-stay behaviour shown in previous studies were explored using the game of Rock, Paper, Scissors and by manipulating the value of winning and losing. Decision-making following a loss was characterized as relatively fast and relatively inflexible both in terms of the failure to modulate the magnitude of lose-shift strategy and the lack of significant neural modulation. In contrast, decision-making following a win was characterized as relatively slow and relatively flexible both in terms of a behavioural increase in the magnitude of win-stay strategy and a neural modulation of feedback-related negativity (FRN) and stimulus-preceding negativity (SPN) following outcome value modulation. The win-stay/lose-shift heuristic appears not to be a unified mechanism, with the former relying on System 2 processes and the latter relying on System 1 processes. Our ability to play rationally appears more likely when the outcome is positive and when the value of wins are low, highlighting how vulnerable we can be when trying to succeed during competition.

Does the Brain’s Reward Response Occur Even Without Actual Reward? A Response to Fielding et al. (2017)

A recent paper by Fielding et al. (J Gamb Stud, 2017) argued that the brain’s reward response could occur without the presentation of actual reward. We suggest that since (a) the event-related potentials reported in this paper are atypical of the previous literature, and, (b) a simpler account of the data in terms of sensitivity to outcome frequency cannot be ruled out, the extent to which the brain’s reward response can occur without the presentation of actual reward should remain an open question.

Failure generates impulsivity only when outcomes cannot be controlled.

Verbruggen, Chambers, Lawrence, and McLaren (2017) recently challenged the view that individuals act with greater caution following the experience of a negative outcome by showing that a gambled loss resulted in faster reaction time (RT) on the next trial. Over three experiments, we replicate and establish the boundary conditions of this effect in the context of a simple game (rock, paper, scissors [RPS]). Choice responding against unexploitable opponents replicated the link between failure and faster responding. However, individuals with high win-rates against exploitable opponents initiated slower rather than faster responding following loss. The data suggest that the link between failure and impulsivity is limited to contexts where participants cannot exert control over outcomes.