How we Can change your mind: Anodal tDCS to Fp3 alters human stimulus representation and learning.

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The aim of the current work is to advance our understanding of both the mechanisms controlling perceptual learning and the face inversion effect. In the three double blind experiments reported here (total N=144) we have shown that anodal tDCS stimulation (10 mins at 1.5 mA) delivered over the left DLPFC at Fp3 affects perceptual learning and drastically reduces the, usually robust, face inversion effect. In Experiment 1, we found a significantly reduced inversion effect in the anodal group compared to that in the sham group. Experiment 2 replicated the pattern of results found in Experiment 1. In both experiments recognition performance for upright faces in the anodal group was significantly impaired compared to that in the sham group. Finally, using an active control in Experiment 3 (same behavioural task but different tDCS targeted brain area) we showed that the same Fp3 anodal tDCS stimulation effect is not obtained when a different brain area is targeted.This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 743702 awarded to Ciro Civile. This project has also received funding from the Economic and Social Research Council (ESRC) New Investigator Grant (Ref. ES/R005532) awarded to Ciro Civile (PI) and I.P.L. McLaren (Co-I)

Mindfulness and Fear Conditioning

This is the final version of the article. Available from the publisher via the link in this record.During mindfulness-based interventions participants can be invited to bring aversive stimuli to mind while practicing mindfulness. This is thought to help the stimuli become less aversive. However, the mechanisms underlying this process are not fully understood. In this study we explored these by examining the effects of mindfulness practice and stimulus visualization on stimuli associated with electric shocks. Participants were trained on a discrimination between two visual stimuli using a standard electrodermal conditioning procedure, in which one stimulus (CS+) was paired with shock and the other (CS-) was not. They then visualized either the CS+ or CS-, while practicing mindfulness or performing a control activity. Following a number of extinction trials, the impact of these manipulations was assessed during a reacquisition test-phase. Both mindfulness and visualization of the CS+ led to slower reacquisition of the CS+/shock association, when measured physiologically, and their effects were additive. Moreover, these effects dissociated from participants’ expectancy of shock. If confirmed in future work, these findings may have implications for the treatment of stimulus-specific anxiety.This research was funded by British Academy / Leverhulme Small Research Grant SG150007

Does Associative Memory Play a Role in Solving Physics Problems?

This is the final version of the article. Available from the publisher via the link in this record.Previous research has found that people frequently provide incorrect predictions about the path of moving objects when given an idealised physics problem to solve. The aim of this research was to explore whether these incorrect predictions are due to the application of an incorrect naïve physics theory, whether incorrect perceptions generated from past experiences lead to misconceptions of how moving objects behave, or whether it is a combination of both. Thirty-one participants volunteered to take part in the experiment which followed a two (experience congruent/incongruent with naïve physics theory) by two (carried versus free-moving object) within-subject design. The dependent variable was participant response (straight down or curved forwards). Results of the study revealed that participants provided answers both consistent and inconsistent with the naïve physics theory. This suggests that responses were primarily elicited through the retrieval of associatively-mediated memories of similar scenarios - some of which contain perceptual illusions. Possible methodological limitations and alternative theoretical explanations are discussed, along with practical and theoretical implications for education and learning

Revisiting peak shift on an artificial dimension: Effects of stimulus variability on generalization

This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this record.One of Mackintosh’s many contributions to the comparative psychology of associative learning was in developing the distinction between the mental processes responsible for learning about features and learning about relations. His research on discrimination learning and generalization served to highlight differences and commonalities in learning mechanisms across species and paradigms. In one such example, Wills and Mackintosh (1998) trained both pigeons and humans to discriminate between two categories of complex patterns comprising overlapping sets of abstract visual features. They demonstrated that pigeons and humans produced similar “peakshifted” generalization gradients when the proportion of shared features was systemically varied across a set of transfer stimuli, providing support for an elemental feature-based analysis of discrimination and generalization. Here we report a series of experiments inspired by this work, investigating the processes involved in post-discrimination generalization in human category learning. We investigate how post-discrimination generalization is affected by variability in the spatial arrangement and probability of occurrence of the visual features, and develop an associative learning model that builds on Mackintosh’s theoretical approach to elemental associative learning

Cue Competition in Human Associative Learning

CogSci 2013 - 35th annual meeting of the Cognitive Science Society, Berlin, Germany, 31 July - 3 August 2013There is a question as to whether cue competition effects can be observed in incidental learning paradigms in humans. The SRT and other location prediction tasks fall into that group often considered to show associative learning under incidental conditions. We used a standard SRT task in which the preceding two trials of a run of three predicted the third 2/3 of the time, and added another predictive cue, a colored square, which could also stochastically predict the next response required. The question was to what extent would these two cues compete in terms of incidental learning to make the next response faster and more accurate than controls? We assessed this by comparing the dual cue group to a color only control and a sequence only control. Our results showed that all three groups learned, and that the dual group learned about both cues at least as well as the individual controls, but that when switched to a test phase where each cue could be assessed independently, the dual group showed a marked decline in performance relative to the color control. We interpret this as evidence for overshadowing occurring between the two predictive cues in the dual group, such that when combined their performance is equivalent or superior to either control, but when assessed independently, the color cue actually has a weaker association to the outcome than the equivalent cue in the control group.This research was supported by an ESRC grant to IPL McLaren and FW Jone

Transcranial Direct Current Stimulation (tDCS) and the Face Inversion Effect: Anodal stimulation at Fp3 reduces recognition for upright faces

This is the final version of the article. Available from the publisher via the link in this record.Perceptual learning is a key perceptual skill that people possess, in particular, it contributes to their ability to distinguish between faces thus recognize individuals. Recently, we showed that anodal transcranial Direct Current Stimulation (tDCS) at Fp3 abolishes the inversion effect (that would otherwise exist) for familiar checkerboards created from a prototype. Because of the close analogy between the inversion effect obtained with checkerboards, which we use as a marker for perceptual learning, and the traditional face inversion effect (upright faces recognized better than inverted ones), we investigated the effects of anodal tDCS at Fp3 during an old/new recognition task for upright and inverted faces. Results showed that stimulation significantly reduced the face inversion effect compared to controls. The effect was strongest in reducing recognition performance to upright faces. This result supports our account of perceptual learning and its role as a key factor in face recognitio

Pigeons in Control of their Actions: Learning and Performance in Stop-Signal and Change-Signal Tasks

This is the author accepted manuscript. The final version is available from the American Psychological Association via the DOI in this record.In human participants, two paradigms commonly assumed to measure the executive-control processes involved in response inhibition are the Stop-Signal and Change-Signal tasks. There is, however, also considerable evidence that performance in these tasks can be mediated by associative processes. To assess which components of inhibitory response control might be associative, we developed analogues of these two tasks for pigeons. We trained pigeons to peck quickly at one of two keys of different colours to obtain a food reward. On some trials, the rewarded key was replaced (after a varying interval) by a signal of a different colour. For some birds, this was a Change Signal: pecking the signal had no effect, but pecking the usually unrewarded alternative key led to a reward, so the response had to be changed. For other birds, the change in colour was a Stop Signal: pecking the alternative key remained ineffective, but pecking the signal now led to a timeout instead of the usual reward, so responses had to be withheld. Pigeons succeeded in both tasks, but performance declined with increasing signal delay. The details of performance in both tasks were consistent with the independent horse-race model of inhibitory control often applied to studies of human participants. This outcome further suggests that stop-signal tasks of the kind used here might not be suitable for assessing top-down executive-control processes in humans

What can Associative Learning do for Driving?

This is the final version of the paper. Available from Cognitive Science Society via the link in this record.To improve road safety, it is important to understand the impact that the contingencies around traffic lights have upon drivers’ behavior. There are formal rules that govern behavior at UK traffic lights (see The Highway Code, 2015), but what does experience of the contingencies do to us? While a green light always cues a go response and a singleton red a stop, the behavior linked to amber is ambiguous; in the presence of red it cues readiness to start, while on its own it cues "preparation" to stop. Could it be that the contingencies between stimuli and responses lead to implicit learning of responses that differ from those suggested by the rules of the road? This study used an incidental go/no-go task in which colored shapes were stochastically predictive of whether a response was required. The stimuli encoded the contingencies between traffic lights and their appropriate responses, for example, stimulus G was a go cue, mimicking the response to a green light. Evidence was found to indicate that G was a go cue, while A (which had the same contingencies as an amber light) was a weak go cue, and that R (a stop cue) was surprisingly responded to as a neutral cue.W.G.N. is supported by an ERSC studentship (ES/J50015X/1)

The Role of Experience-based Perceptual Learning in the Face Inversion Effect

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Perceptual learning of the type we consider here is a consequence of experience with a class of stimuli. It amounts to an enhanced ability to discriminate between stimuli. We argue that it contributes to the ability to distinguish between faces and recognize individuals, and in particular contributes to the face inversion effect (better recognition performance for upright vs inverted faces). Previously, we have shown that experience with a prototype defined category of checkerboards leads to perceptual learning, that this produces an inversion effect, and that this effect can be disrupted by Anodal tDCS to Fp3 during pre-exposure. If we can demonstrate that the same tDCS manipulation also disrupts the inversion effect for faces, then this will strengthen the claim that perceptual learning contributes to that effect. The important question, then, is whether this tDCS procedure would significantly reduce the inversion effect for faces; stimuli that we have lifelong expertise with and for which perceptual learning has already occurred. Consequently, in the experiment reported here we investigated the effects of anodal tDCS at Fp3 during an old/new recognition task for upright and inverted faces. Our results show that stimulation significantly reduced the face inversion effect compared to controls. The effect was one of reducing recognition performance for upright faces. This result is the first to show that tDCS affects perceptual learning that has already occurred, disrupting individuals’ ability to recognize upright faces. It provides further support for our account of perceptual learning and its role as a key factor in face recognition

Instructed and acquired contingencies in response-inhibition tasks

This is the author accepted manuscript. The final version is available from Ubiquity Press via the DOI in this record.Inhibitory control can be triggered directly via the retrieval of previously acquired stimulusstop associations from memory. However, a recent study suggests that this item-specific stop learning may be mediated via expectancies of the contingencies in play (Best, Lawrence, Logan, McLaren, & Verbruggen, 2016). This could indicate that stimulus-stop learning also induces strategic, proactive changes in performance. We further tested this hypothesis in the present study. In addition to measuring expectancies following task completion, we introduced a between-subjects expectancy manipulation in which one group of participants were informed about the stimulus-stop contingencies and another group did not receive any information about the stimulus-stop contingencies. Moreover, we combined this instruction manipulation with a distractor manipulation that was previously used to examine strategic proactive adjustments. We found that the stop-associated items slowed responding in both conditions. Furthermore, participants in both conditions generated expectancies following task completion that were consistent with the stimulus-stop contingencies. The distractor manipulation was ineffective. However, we found differences in the relationship between the expectancy ratings and task performance: in the instructed condition, the expectancies reliably correlated with the response slowing for the stop-associated items, whereas in the uninstructed condition we found no reliable correlation. These differences between the correlations were reliable, and our conclusions were further supported by Bayesian analyses. We conclude that stimulus-stop associations that are acquired either via task instructions or via task practice have similar effects on behavior but could differ in how they elicit response slowing.Economic and Social Research Council (ESRC