Modulating perceptual learning indexed by the face inversion effect: Simulating the application of transcranial direct current stimulation using the MKM model.

We report here two large studies investigating the effects of an established transcranial direct current stimulation (tDCS) procedure on perceptual learning as indexed by the face inversion effect. Experiments 1a and 1b (n = 128) examined the harmful generalization from Thatcherized faces to normal faces by directly comparing the size of the inversion effect for normal faces when presented intermixed with Thatcherized faces (Experiment 1a) versus that obtained when normal faces were presented intermixed with checkerboards (Experiment 1b). The results from the sham/control tDCS groups provide the first direct evidence in the literature showing how Thatcherized faces generalize onto normal ones producing a reduced inversion effect compared to when normal faces are presented with stimuli (e.g., checkerboards) that do not generalize significantly to normal faces. In the anodal tDCS groups, this effect was reversed, with a larger inversion effect recorded for normal faces in Experiment 1a versus that found in Experiment 1b. Further analyses within each experiment confirmed that the anodal tDCS procedure can enhance the inversion effect for normal faces in circumstances where harmful generalization would otherwise be produced by the Thatcherized faces (Experiment 1a). We also demonstrated our standard reduction in the inversion effect for normal faces consequent on the application of tDCS when presented intermixed with stimuli that do not generalize onto them. We interpret our results in terms of simulations using the MKM model of perceptual and associative learning. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Using transcranial direct current stimulation (tDCS) to influence decision criterion in a target detection paradigm.

In this article we investigate how a psychological theory used to model perceptual learning and face recognition can be used to predict that anodal tDCS delivered over the DLPFC at Fp3 site (for 10 mins duration at 1.5 mA intensity) modulates the decision criterion, C, (and not d-prime [d']) in a target detection task. In two between-subjects and double-blind experiments (n = 112) we examined the tDCS effects on C when subjects were engaged in a target detection task, in the first instance involving artificial checkerboard stimuli (Experiment 1a), and subsequently face stimuli (Experiment 1b). The results from both experiments revealed that in the sham/control groups a significantly higher C was used when detecting a target pattern (Experiment 1a) or face (Experiment 1b) presented on a familiar rather than a random background. Importantly, anodal tDCS significantly reduced/reversed this difference between C adopted for familiar and random backgrounds in both Experiment 1a and 1b without affecting d'. These results contribute to advance our understanding of the tDCS-induced effects on stimulus representation and to the literature regarding the modulation of C. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Latent inhibition in young children: A developmental effect?

Previous research by Kaniel & Lubow in 1986 found that young children (aged 4-5 years) exhibited poorer learning (latent inhibition) to preexposed stimuli than older children (aged 7-10 years). The aim of our research was to develop a computer-based, child-friendly study that would replicate and extend the work of Kaniel & Lubow in a way that ruled out other, attention-based explanations of their effect. One hundred and four children and 32 undergraduate students took part in our experiment. This consisted of a preexposure/study phase in which participants were asked to press computer keys in response to clipart pictures of animals and dinosaurs. Each animal or dinosaur picture was preceded by one of 2 "warning signals" that acted as the preexposed stimuli (to which no response was required). In the test phase that followed, the participants had to either press the spacebar or withhold their response to each preexposed stimulus and two novel stimuli. They learned which response was correct by trial and error using the feedback provided. The accuracy and reaction time (RT) of the responses during the test phase were analyzed and indicated that the youngest children showed significantly lower mean accuracy and longer mean response times to the preexposed stimuli than to stimuli they had not been preexposed to. In contrast, the older children showed no significant differences in their responses to preexposed and novel stimuli. These results are consistent with those found by Kaniel & Lubow and as such provide additional evidence for latent inhibition in young children. We discuss the implications for theories of perceptual learning in humans. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The effects of transcranial direct current stimulation on perceptual learning for upright faces and its role in the composite face effect.

In the 3 experiments reported here we show that a specific neurostimulation method, whose influence can be understood in terms of a well-known theory of stimulus representation, is able to affect face recognition skills by impairing participants' performance for upright faces. We used the transcranial Direct Current Stimulation (tDCS) procedure we have recently developed that allows perceptual learning, as indexed by the face inversion effect, to be modulated. We extended this tDCS procedure to another phenomenon, the composite face effect, which constitutes better recognition of the top half of an upright face when conjoined with a congruent (in terms of the response required) rather than incongruent bottom half. All three experiments used the Face-Matching task traditionally used to study this phenomenon. Experiment 1a (n = 48) showed that anodal tDCS (using a double-blind between-subjects design) delivered at Fp3 (10 mins at 1.5 mA) affected overall performance for upright faces compared with sham but had no effect on the composite face effect itself. Experiment 1b (n = 48) replicated our usual tDCS-induced effects on the face inversion effect but this time using a Face-Matching task instead of the old/new recognition task previously used to obtain the effect. Experiment 2 (n = 72) replicated the findings from Experiment 1a, and, using an active control group, showed that the Fp3 anodal tDCS effects on performance to upright faces are not obtained when a different brain area is targeted. We interpret our results in the light of previous literature on the tDCS effects on perceptual learning and face recognition and suggest that different mechanisms are involved in the face inversion effect and the composite face effect. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Using transcranial Direct Current Stimulation (tDCS) to investigate why faces are and are not special.

We believe we are now in a position to answer the question, "Are faces special?" inasmuch as this applies to the face inversion effect (better performance for upright vs inverted faces). Using a double-blind, between-subject design, in two experiments (n = 96) we applied a specific tDCS procedure targeting the Fp3 area while participants performed a matching-task with faces (Experiment 1a) or checkerboards from a familiar prototype-defined category (Experiment 1b). Anodal tDCS eliminated the checkerboard inversion effect reliably obtained in the sham group, but only reduced it for faces (although the reduction was significant). Thus, there is a component to the face inversion effect that we are not affecting with a tDCS procedure that can eliminate the checkerboard inversion effect. We suggest that the reduction reflects the loss of an expertise-based component in the face inversion effect, and the residual is due to a face-specific component of that effect.

Testing the effects of transcranial direct current stimulation (tDCS) on the face inversion effect and the N170 event-related potentials (ERPs) component.

The following study investigates the effects of tDCS on face recognition skills indexed by the face inversion effect (better recognition performance for upright vs. inverted faces). We combined tDCS and EEG simultaneously to examine the effects of tDCS on the face inversion effect behaviourally and on the N170 ERPs component. The results from two experiments (overall N = 112) show that anodal tDCS delivered at Fp3 site for 10 min at 1.5 mA (double-blind and between-subjects) can reduce behaviourally the face inversion effect compared to sham (control) stimulation. The ERP results provide some evidence for tDCS being able to influence the face inversion effect on the N170. Specifically, we find a dissociation of the tDCS-induced effects where for the N170 latencies the tDCS reduces the usual face inversion effect (delayed N170 in response to inverted vs. upright faces) compared to sham. Contrarily, the same tDCS procedure on the same participants increased the inversion effect seen in the N170 amplitudes by making the negative deflection for the inverted faces that much greater than that for upright faces. We interpret our results in the context of the literature on the face inversion effect and the N170 peak component. In doing so, we extend our results to previous studies investigating the effects of tDCS on perceptual learning and face recognition.

The effect of tDCS on recognition depends on stimulus generalization: Neuro-stimulation can predictably enhance or reduce the face inversion effect.

This article reports results from three experiments that investigate how a particular neuro-stimulation procedure is able, in certain circumstances, to selectively increase the face inversion effect by enhancing recognition for upright faces, and argues that these effects can be understood in terms of the McLaren-Kaye-Mackintosh (MKM) theory of stimulus representation. We demonstrate how a specific transcranial direct current stimulation (tDCS) methodology can improve performance in circumstances where error-based salience modulation is making face recognition harder. The 3 experiments used an old/new recognition task involving sets of normal versus Thatcherized faces. The main characteristic of Thatcherized faces is that the eyes and the mouth are upside down, thus emphasizing features that tend to be common to other Thatcherized faces and so leading to stronger generalization making recognition worse. Experiment 1 combined a behavioral and event-related potential study looking at the N170 peak component, which helped us to calibrate the set of face stimuli needed for subsequent experiments. In Experiment 2, we used our tDCS procedure (between-subjects and double-blind) in an attempt to reduce the negative effects induced by error-based modulation of salience on recognition of upright Thatcherized faces. Results largely confirmed our predictions. In addition, they showed a significant improvement on recognition performance for upright normal faces. Experiment 3 provides the first direct evidence in a single study that the same tDCS procedure is able to both enhance performance when normal faces are presented with Thatcherized faces, and to reduce performance when normal faces are presented with other normal faces (i.e., male vs. female faces). We interpret our results by analyzing how salience modulation influences generalization between similar categories of stimuli. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Mackintosh lecture-: Association and cognition: Two processes, one system.

This article argues that the dual-process position can be a useful first approximation when studying human mental life, but it cannot be the whole truth. Instead, we argue that cognition is built on association, in that associative processes provide the fundamental building blocks that enable propositional thought. One consequence of this position is to suggest that humans are able to learn associatively in a similar fashion to a rat or a pigeon, but another is that we must typically suppress the expression of basic associative learning in favour of rule-based computation. This stance conceptualises us as capable of symbolic computation but acknowledges that, given certain circumstances, we will learn associatively and, more importantly, be seen to do so. We present three types of evidence that support this position: The first is data on human Pavlovian conditioning that directly support this view. The second is data taken from task-switching experiments that provide convergent evidence for at least two modes of processing, one of which is automatic and carried out "in the background." And the last suggests that when the output of propositional processes is uncertain, the influence of associative processes on behaviour can manifest.

The effect of scrambling upright and inverted faces on the N170.

The face inversion effect refers to a decrement in performance when we try to recognise familiar faces turned upside down (inverted), compared with familiar faces presented in their usual (upright) orientation. Recently, we have demonstrated that the inversion effect can also be found with checkerboards drawn from prototype-defined categories when the participants have been trained with these categories, suggesting that factors such as expertise and the relationships between stimulus features may be important determinants of this effect. We also demonstrated that the typical inversion effect on the N170 seen with faces is found with checkerboards, suggesting that modulation of the N170 is a marker for disruption in the use of configural information. In the present experiment, we first demonstrate that our scrambling technique greatly reduces the inversion effect in faces. Following this, we used Event-Related Potentials ( ERPs) recorded while participants performed an Old/New recognition study on normal and scrambled faces presented in both upright and inverted orientations to investigate the impact of scrambling on the N170. We obtained the standard robust inversion effect for normal faces: The N170 was both larger and delayed for normal inverted faces as compared with normal upright faces, whereas a significantly reduced inversion effect was recorded for scrambled faces. These results show that the inversion effect on the N170 is greater for normal compared with scrambled faces, and we interpret the smaller effect for scrambled faces as being due to the reduction in expertise for those faces consequent on scrambling.

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

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 min 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.

Structure and Implementation of Novel Task Rules: A Cross-Sectional Developmental Study.

Rule-based performance improves remarkably throughout childhood. The present study examined how children and adolescents structured tasks and implemented rules when novel task instructions were presented in a child-friendly version of a novel instruction-learning paradigm. Each miniblock started with the presentation of new stimulus-response mappings for a go task. Before this mapping could be implemented, subjects had to make responses in order to advance through screens during a preparatory (" next") phase. Children (4-11 years old) and late adolescents (17-19 years old) responded more slowly during the next phase when the next response was incompatible with the instructed stimulus-response mapping. This instruction-based interference effect was more pronounced in young children than in older children. We argue that these findings are most consistent with age-related differences in rule structuring. We discuss the implications of our findings for theories of rule-based performance, instruction-based learning, and development.

Development of between-trial response strategy adjustments in a continuous action control task: A cross-sectional study.

Response strategies are constantly adjusted in ever-changing environments. According to many researchers, this involves executive control. This study examined how children (aged 4-11years) and young adults (aged 18-21years) adjusted response strategies in a continuous action control task. Participants needed to move a stimulus to a target location, but on a minority of the trials (change trials) the target location changed. When this happened, participants needed to change their movement. We examined how performance was influenced by the properties of the previous trial. We found that no-change performance was impaired, but change performance was improved, when a change signal was presented on the previous trial. Extra analyses revealed that the between-trial effects on no-change trials were not influenced by the repetition of the previous stimulus. Combined, these findings provide support for the idea that response strategies were adjusted on a trial-by-trial basis. Importantly, we observed large age-related differences in overall change and no-change latencies but observed no differences in response strategy adjustments. This is consistent with findings obtained with other paradigms and suggests that adjustment mechanisms mature at a faster rate than other "executive" action control mechanisms.

Switching off perceptual learning: Anodal transcranial direct current stimulation (tDCS) at Fp3 eliminates perceptual learning in humans.

Perceptual learning can be acquired as a result of experience with stimuli that would otherwise be difficult to tell apart, and is often explained in terms of the modulation of feature salience by an error signal based on how well that feature can be predicted by the others that make up the stimulus. In this article we show that anodal transcranial Direct Current Stimulation (tDCS) at Fp3 directly influences this modulation process so as to eliminate and possibly reverse perceptual learning. In 2 experiments, anodal stimulation disrupted perceptual learning (indexed by an inversion effect) compared with sham (Experiment 1) or cathodal (Experiment 2) stimulation. Our findings can be interpreted as showing that anodal tDCS severely reduced or even abolished the modulation of salience based on error, greatly increasing generalization between stimuli. This result supports accounts of perceptual learning based on variations in salience as a consequence of pre-exposure, and opens up the possibility of controlling this phenomenon. (PsycINFO Database Record

The Face Inversion Effect: Roles of First- and Second-Order Configural Information.

The face inversion effect (FIE) is a reduction in recognition performance for inverted faces compared with upright faces. Several studies have proposed that a type of configural information, called second-order relational information, becomes more important with increasing expertise and gives rise to the FIE. However, recently it has been demonstrated that it is possible to obtain an FIE with facial features presented in isolation, showing that configural information is not necessary for this effect to occur. In this article we test whether there is a role for configural information in producing the FIE and whether second- or first-order relational information is particularly important. In Experiment 1, we investigated the role of configural information and local feature orientation by using a new type of "Thatcherizing" transformation on our set of faces, aiming to disrupt second-order and local feature orientation information but keeping all first-order properties unaltered. The results showed a significant reduction in the FIE for these "new" Thatcherized faces, but it did not entirely disappear. Experiment 2 confirmed the FIE for new Thatcherized faces, and Experiment 3 establishes that both local feature orientation and first-order relational information have a role in determining the FIE.

The face inversion effect--parts and wholes: individual features and their configuration.

The face inversion effect (FIE) is a reduction in recognition performance for inverted faces (compared to upright faces) that is greater than that typically observed with other stimulus types (e.g., houses). The work of Diamond and Carey, suggests that a special type of configural information, "second-order relational information" is critical in generating this inversion effect. However, Tanaka and Farah concluded that greater reliance on second-order relational information did not directly result in greater sensitivity to inversion, and they suggested that the FIE is not entirely due to a reliance on this type of configural information. A more recent review by McKone and Yovel provides a meta-analysis that makes a similar point. In this paper, we investigated the contributions made by configural and featural information to the FIE. Experiments 1a and1b investigated the link between configural information and the FIE. Remarkably, Experiment 1b showed that disruption of all configural information of the type considered in Diamond and Carey's analysis (both first and second order) was effective in reducing recognition performance, but did not significantly impact on the FIE. Experiments 2 and 3 revealed that face processing is affected by the orientation of individual features and that this plays a major role in producing the FIE. The FIE was only completely eliminated when we disrupted the single feature orientation information in addition to the configural information, by using a new type of transformation similar to Thatcherizing our sets of scrambled faces. We conclude by noting that our results for scrambled faces are consistent with an account that has recognition performance entirely determined by the proportion of upright facial features within a stimulus, and that any ability to make use of the spatial configuration of these features seems to benefit upright and inverted normal faces alike.