Transcranial Direct Current Stimulation and Decision-Making: The Neuromodulation of Cognitive Reflection

The ability to make judgements and decisions is crucial to our lives. The dual-process framework of judgement and decision-making (e.g. Stanovich, 2009) proposes that decisions are usually made using mental processes relying on automatic processes (called Type 1 processing) or on more controlled processes (called Type 2 processing). According to this theory, when we make a decision without conscious effort we rely on the autonomous processes of Type 1 intuitive thinking, which is prone towards errorful decision-making. Alternatively, if we use Type 2 thinking by committing cognitive resources (e.g., working memory) we engage analytic thinking by at least partly inhibiting Type 1 processing. The primary goal for this thesis is to test whether Type 1 versus Type 2 processes in decision-making can be linked to different neural substrates. Transcranial direct current stimulation (tDCS), a non-invasive method for enhancing or decreasing cortical excitability was used. Participants completed decision-making tasks (e.g., Cognitive Reflection Test (CRT), syllogistic reasoning) to capture performance indicating Type 1 or Type 2 processing, and executive function tasks to assess the basis of Type 1 and Type 2 processing. First, a meta-analysis was performed on a variety of experiments using tDCS, finding evidence for the involvement of frontal structures in judgement and decision-making. In subsequent experiments stimulation of the right but not left dorsolateral prefrontal cortex (DLPFC) with anodal tDCS increased performance compared to sham in the CRT and solving vignettes measuring heuristic thinking. In experiment three there was a cumulative effect of neuromodulation on Type 2 processing, with an increase in reflective thinking performance following each of two stimulation sessions. Individual differences in thinking dispositions and cognitive ability could not explain the results, and there were no performance-enhancing effects of stimulation on syllogisms or executive functions. These experiments provide evidence for the involvement of the right DLPFC in decision-making which relies on the inhibition of pre-potent responses (e.g., the CRT)

Efficacy and acceptability of non-invasive brain stimulation for the treatment of adult unipolar and bipolar depression: A systematic review and meta-analysis of randomised sham-controlled trials

We examined the efficacy and acceptability of non-invasive brain stimulation in adult unipolar and bipolar depression. Randomised sham-controlled trials of transcranial direct current stimulation (tDCS), transcranial magnetic stimulation (TMS) and theta-burst stimulation (TBS), without co-initiation of another treatment, were included. We analysed effects on response, remission, all-cause discontinuation rates and continuous depression severity measures. Fifty-six studies met our criteria for inclusion (N = 3,058, mean age = 44.96 years, 61.73% female). Response rates demonstrated efficacy of high-frequency rTMS over the left DLPFC (OR = 3.75, 95% CI [2.44; 5.75]), right-sided low-frequency rTMS (OR = 7.44, 95%CI [2.06; 26.83]) bilateral rTMS (OR = 3.68,95%CI [1.66; 8.13]), deep TMS (OR = 1.69, 95%CI [1.003; 2.85]), intermittent TBS (OR = 4.70, 95%CI [1.14; 19.38]) and tDCS (OR = 4.17, 95% CI [2.25; 7.74]); but not for continuous TBS, bilateral TBS or synchronised TMS. There were no differences in all-cause discontinuation rates. The strongest evidence was for high-frequency rTMS over the left DLPFC. Intermittent TBS provides an advance in terms of reduced treatment duration. tDCS is a potential treatment for non-treatment resistant depression. To date, there is not sufficient published data available to draw firm conclusions about the efficacy and acceptability of TBS and sTMS

Anodal transcranial direct current stimulation over the right dorsolateral prefrontal cortex enhances reflective judgment & decision-making

Background: Accounts of cognitive processes in judgment and decision-making are frequently based on a dual-process framework, which reflects two qualitatively different types of processing: intuitive (Type 1) and analytical (Type 2) processes. Objective/hypothesis: The present study investigated the effects of bilateral transcranial direct current stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC) on judgment and decision-making performance. Methods: Participants received anodal tDCS stimulation to the right DLPFC, left DLPFC or sham. There were 3 tasks: vignettes measuring heuristic thinking, belief bias syllogisms, and the cognitive reflection test (CRT), a measure of the ability to inhibit automatic responses to reach a correct solution. Fifty-four participants (mean age = 24.63 + 4.46 years; 29 females) were recruited. Results: Results showed that anodal tDCS to the right DLPFC was associated with an increase in cognitive reflection performance (Type 2 processing) as compared to left DLPFC and to sham. Logic thinking was reduced following anodal tDCS to the left DLPFC. Conclusion: These findings are broadly consistent with a dual process framework, which cannot be explained by differences in cognitive ability and thinking style. The results demonstrate the involvement of the right DLPFC in cognitive reflection and suggest the possibility of improving cognitive performance through tDCS

Confirmation bias in decision making for fingerprints, DNA and eyewitness evidence cannot be explained by cognitive style or thinking dispositions.

Pre-existing beliefs about the background or guilt of a suspect can bias the subsequent evaluation of evidence for forensic examiners and lay people alike. This biasing effect, called the confirmation bias, has influenced legal proceedings in prominent court cases such as that of Brandon Mayfield. Today many forensic providers attempt to train their examiners against these cognitive biases. Nine hundred and forty-two participants read a fictional criminal case and received either neutral, incriminating or exonerating evidence (fingerprint, eyewitness, or DNA) before providing an initial rating of guilt. Participants then viewed ambiguous evidence (alibi, facial composite, handwriting sample or informant statement) before providing a final rating of guilt. Final guilt ratings were higher for all evidence conditions (neutral, incriminating or exonerating) following exposure to the ambiguous evidence. This provides evidence that the confirmation bias influences the evaluation of evidence

Edgcumbe. 2019 - The relationship between cognitive reflection and morality judgments are mediated by thinking dispositions.

Abstract: Performance on Cognitive Reflection Test (CRT) is thought to predict moral judgments concerning the Moral Foundations Questionnaire (MFQ). This relationship is hypothesised to be mediated by the tendency toward thinking dispositions such as actively open-minded thinking (AOT), rational (REI-R) and experiential thinking (REI-E), and religiosity. The relationship between cognitive reflection, intuitive thinking and moral judgments with thinking dispositions are examined. As the MFQ measures five types of moral judgments which include ‘individualising values’ – harm and fairness, and ‘binding values’ - loyalty, authority and purity it was hypothesised that performance on these moral foundations would be influenced by thinking dispositions and cognitive reflection. Results indicate that the relationship between cognitive reflection and moral judgments were mediated differently by thinking dispositions. Religious participants and intuitive thinkers alike scored highly on binding moral values. Analytic thinkers and non-religious participants scored highly on individualising moral values. The data is consistent with religiosity and intuition being inherently linked and suggests that moral values are influenced by individual differences in thinking dispositions and cognitive style

PrePrint Version (Edgcumbe, 2020): The developmental trajectory of open-mindedness: from 18 to 87-years of age.

Objectives: The present study examined the role of aging in participants between 18 and 87-years of age on open-mindedness in the Actively Open-minded Thinking (AOT) scale and the Actively Open-minded Thinking about Evidence (AOT-E) scale. Method: The amalgamated data from 12 Amazon Mechanical Turk™ studies was analysed. This included a total of 9010 participants (age: M = 37.30, SD = 14.13 / sex: 4191 males, 4734 females and 85 who did not wish to state their sex). All participants completed the 7-item Actively Open-minded Thinking (AOT) scale, of these participants four-hundred and ninety-one also completed the 8-item Actively Open-minded Thinking about Evidence (AOT-E) scale (age: M = 33.27, SD = 5.78 / sex: 2317 males, 2512 females and 62 who did not wish to state their sex). Results: AOT score positively correlated with AOT-E score (r = 0.27). Age negatively correlated with AOT score (r = -0.11) and AOT-E score (r = -0.13). There was a statistical difference in AOT score between the age ranges of participants (18-28, 29-38, 39-48, 49-58, 59-68 and 69-87 years of age). There was also a difference in AOT-E score between the age ranges of participants too. Discussion: The results showed that open-mindedness as measured by the AOT and AOT-E decreased as a function of aging. In an aging population were more adults work into later age the decrease in open-mindedness could influence many areas of judgments of decision-making

Zinc as a subsoil nutrient for cereals / by R.E. Holloway.

Bibliography: leaves 290-324.xxii, 324 leaves, [5] leaves of plates : col. ill. ; 30 cm.This thesis investigates two avenues suggested by Graham and Ascher (1993) for approaching the problems of subsoil infertility, with particular reference to zinc. Field experiments with wheat and barley were established at Minnipa, on Eyre Peninsula in South Australia to investigate the effects of applying nutrients (principally zinc, nitrogen and phosphorus) to the subsoil to a depth of 0.4 m with a modified deep ripper. A deep pot experiment was designed to measure the zinc efficiencies (in terms of dry matter production) of a range of species grown in siliceous sand. The effects of added zinc on root growth were compared. A pot experiment was also designed to measure the effects of zinc placement in the soil on the zinc concentrations and uptake in Excalibur, particularly with respect to concentrations in grain.Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 199