Allan Snyder

Explaining and inducing savant skills: privileged access to lower level, less-processed information

I argue that savant skills are latent in us all. My hypothesis is that savants have privileged access to lower level, less-processed information, before it is packaged into holistic concepts and meaningful labels. Owing to a failure in top-down inhibition, they can tap into information that exists in all of our brains, but is normally beyond conscious awareness. This suggests why savant skills might arise spontaneously in otherwise normal people, and why such skills might be artificially induced by low-frequency repetitive transcranial magnetic stimulation. It also suggests why autistic savants are atypically literal with a tendency to concentrate more on the parts than on the whole and why this offers advantages for particular classes of problem solving, such as those that necessitate breaking cognitive mindsets. A strategy of building from the parts to the whole could form the basis for the so-called autistic genius. Unlike the healthy mind, which has inbuilt expectations of the world (internal order), the autistic mind must simplify the world by adopting strict routines (external order).

Facilitate Insight by Non-Invasive Brain Stimulation

Our experiences can blind us. Once we have learned to solve problems by one method, we often have difficulties in generating solutions involving a different kind of insight. Yet there is evidence that people with brain lesions are sometimes more resistant to this so-called mental set effect. This inspired us to investigate whether the mental set effect can be reduced by non-invasive brain stimulation. 60 healthy right-handed participants were asked to take an insight problem solving task while receiving transcranial direct current stimulation (tDCS) to the anterior temporal lobes (ATL). Only 20% of participants solved an insight problem with sham stimulation (control), whereas 3 times as many participants did so (pu200a=u200a0.011) with cathodal stimulation (decreased excitability) of the left ATL together with anodal stimulation (increased excitability) of the right ATL. We found hemispheric differences in that a stimulation montage involving the opposite polarities did not facilitate performance. Our findings are consistent with the theory that inhibition to the left ATL can lead to a cognitive style that is less influenced by mental templates and that the right ATL may be associated with insight or novel meaning. Further studies including neurophysiological imaging are needed to elucidate the specific mechanisms leading to the enhancement.

Temporal Lobe Cortical Electrical Stimulation during the Encoding and Retrieval Phase Reduces False Memories

A recent study found that false memories were reduced by 36% when low frequency repetitive transcranial magnetic stimulation (rTMS) was applied to the left anterior temporal lobe after the encoding (study) phase. Here we were interested in the consequences on a false memory task of brain stimulation throughout the encoding and retrieval task phases. We used transcranial direct current stimulation (tDCS) because it has been shown to be a useful tool to enhance cognition. Specifically, we examined whether tDCS can induce changes in a task assessing false memories. Based on our preliminary results, three conditions of stimulation were chosen: anodal left/cathodal right anterior temporal lobe (ATL) stimulation (“bilateral stimulation”); anodal left ATL stimulation (with a large contralateral cathodal electrode – referred as “unilateral stimulation”) and sham stimulation. Our results showed that false memories were reduced significantly after the two active conditions (unilateral and bilateral stimulation) as compared with sham stimulation. There were no significant changes in veridical memories. Our findings show that false memories are reduced by 73% when anodal tDCS is applied to the anterior temporal lobes throughout the encoding and retrieval stages, suggesting a possible strategy for improving certain aspects of learning.

Visual memory improved by non-invasive brain stimulation.

Our visual memories are susceptible to errors, but less so in people who have a more literal cognitive style. This inspired us to attempt to improve visual memory with non-invasive brain stimulation. We applied 13 min of bilateral transcranial direct current stimulation (tDCS) to the anterior temporal lobes. Our stimulation protocol included 3 conditions, each with 12 neurotypical participants: (i) left cathodal stimulation together with right anodal stimulation, (ii) left anodal stimulation together with right cathodal stimulation, and (iii) sham (control) stimulation. Only participants who received left cathodal stimulation (decrease in excitability) together with right anodal stimulation (increase in excitability) showed an improvement in visual memory. This 110% improvement in visual memory was similar to the advantage people with autism, who are known to be more literal, show over normal people in the identical visual task. Importantly, participants receiving stimulation of the opposite polarity (left anodal together with right cathodal stimulation) failed to show any change in memory performance. This is the first demonstration that visual memory can be enhanced in healthy people using non-invasive brain stimulation.

Savant-like numerosity skills revealed in normal people by magnetic pulses.

Oliver Sacks observed autistic twins who instantly guessed the exact number of match-sticks that had just fallen on the floor, saying in unison “111”. To test the suggestion that normal individuals have the capacity for savant numerosity, we temporarily simulated the savant condition in normal people by inhibiting the left anterior temporal lobe of twelve participants with repetitive transcranial magnetic stimulation (rTMS). This site has been implicated in the savant condition. Ten participants improved their ability to accurately guess the number of discrete items immediately following rTMS and, of these, eight became worse at guessing as the effects of the pulses receded. The probability of as many as eight out of twelve people doing best just after rTMS and not after sham stimulation by chance alone is less than one in one thousand.

The Incubation Effect: Hatching a Solution?

Numerous anecdotal accounts exist of an incubation period promoting creativity and problem solving. This article examines whether incubation is an empirically verifiable phenomenon and the possible role therein of nonconscious processing. An Idea Generation Test was employed to examine (a) whether an incubation effect occurred and (b) the impact of different types of break on this effect. In the Idea Generation Test, two groups of participants were given a distracting break, during which they completed either a similar or an unrelated task, and a third group worked continuously (N = 90). The Idea Generation Test was validated against established measures of cognitive ability and personality, and was found to exhibit variance distinct from those marker tests. Most important, results demonstrated that having a break during which one works on a completely different task is more beneficial for idea production than working on a similar task or generating ideas continuously. The advantage afforded by a break cannot be accounted for in terms of relief from functional fixedness or general fatigue, and, although it may be explicable by relief from task-specific fatigue, explanations of an incubation effect in terms of nonconscious processing should be (re)considered.

Brain stimulation enables the solution of an inherently difficult problem.

Certain problems are inherently difficult for the normal human mind. Yet paradoxically they can be effortless for those with an unusual mind. We discovered that an atypical protocol for non-invasive brain stimulation enabled the solution of a problem that was previously unsolvable. The majority of studies over the last century find that no participants can solve the nine-dot problem - a fact we confirmed. But with 10 min of right lateralising transcranial direct current stimulation (tDCS), more than 40% of participants did so. Specifically, whereas no participant solved this extremely difficult problem before stimulation or with sham stimulation, 14 out of 33 participants did so with cathodal stimulation of the left anterior temporal lobe together with anodal stimulation of the right anterior temporal lobe. This finding suggests that our stimulation paradigm might be helpful for mitigating cognitive biases or dealing with a broader class of tasks that, although deceptively simple, are nonetheless extremely difficult due to our cognitive makeup.

Reducing false memories by magnetic pulse stimulation

False memories are ubiquitous and often to our detriment. Yet, certain pathologies, including anterior temporal lobe dementia and autism, can lead to literal recall and thus greater resistance to false memories. This inspired us to reduce false memories by temporarily inhibiting the left anterior temporal lobe, using low frequency magnetic pulse stimulation. This site has been implicated in semantic memory and conceptual labelling. After active stimulation, participants in the sham/TMS group had 36% fewer false memories than they had with sham stimulation, and intact veridical memory. This is comparable to the improvement that people with autism and semantic dementia show over normal individuals. This finding suggests a potential method for reducing certain types of false memories.

Noninvasive Brain Stimulation Reduces Prejudice Scores on an Implicit Association Test

OBJECTIVEnInhibiting the anterior temporal lobe (ATL) via repetitive transcranial magnetic stimulation (rTMS) appears to have deleterious effects on peoples semantic conceptualization, and left ATL damage is associated with semantic dementia. However, little research has investigated whether rTMS can inhibit conceptual schemata that have potentially negative consequences. Our aim was to investigate whether rTMS to the ATLs could reduce scores on a standard measure of prejudice (implicit association test, IAT).nnnMETHODnForty (17 female; mean age 20.6) neurologically normal, right-handed undergraduates participated. Participants were randomly allocated into one of four rTMS stimulation conditions-left ATL, right ATL, control site (motor cortex, Cz), and sham stimulation. All participants completed a modified IAT, where good and bad words were replaced with terrorist and law-abider words, and, Black and White were replaced with Arab and Non-Arab words. Participants were then given 15 min of rTMS stimulation. Afterward, participants completed a parallel form of the IAT.nnnRESULTSnTo investigate the effects of rTMS on IAT scores, a one-way ANOVA on the difference between pre- and postscores was carried out revealing that there were significant between group differences (F3,36 = 3.57; p = .02). Planned contrasts revealed that both left and right ATL stimulation significantly reduced IAT scores poststimulation, indicating lower prejudice.nnnCONCLUSIONnWe show that prejudice scores can be significantly reduced by inhibitory rTMS delivered to the bilateral ATLs. This may implicate this area in conceptual associations that lead to overgeneralization and stereotyping of social groups.

Creative People Use Nonconscious Processes to Their Advantage

Although contentious, there is evidence to suggest that nonconscious processes contribute to creative output, particularly during refractory periods. However, no one has examined whether this break benefit differs as a function of creative ability. To address these issues, this investigation examined Wallass (1926) seminal theoretical framework of creativity. More specifically, the most controversial stage postulated by Wallas, the incubation phase, was empirically tested. A regression analysis demonstrated that productivity is significantly increased when creative people activate nonconscious processes in off-task or incubation periods. There is ongoing debate about the cause(s) of this incubation effect. This research provides evidence that the incubation effect results, at least partially, from nonconscious processing and that it provides greater benefit to more creative individuals. This suggests that highly creative people should be exposed to focus problems/challenges well in advance of objective deadlines, and have freedom to generate solutions outside of structured evaluation times.