Millisecond Gambling Task

Background

The Millisecond Gambling Task (MGT) is a computerized cognitive assessment test of decision-making and risk-taking behavior outside of a learning context. It evaluates how well a person makes choices and places wagers using visible odds. The MGT is inspired by the Cambridge Gambling Task (CGT) by R.D. Rogers and colleagues (1999) which is a subtest of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The CGT is often used to study impulsivity and risk-seeking in substance use disorders and problem gambling.

The task is simple: ten boxes in blue and red boxes (colors are presented in different ratios) are presented on screen, and participants are told that one of these boxes contains a yellow coin. Participants are then tasked with betting money on one of the two colors before the exact token location (and winning color) is revealed. If they win their bet, their bet money is added to their total amount; however, if they lose, their bet money is subtracted from their total. Variables of interest include a person's ability to understand winning probabilities based on the color distribution of the 10 boxes, bet impulsivity, sensitivity to the relationship between bet amounts and win probabilities as well as bet processing times.

Task Procedure

The MGT runs three phases: a practice block followed by two test blocks that present the bet amounts in ascending and descending order. The practice block simply practices picking the probable color (red or blue) of the box that hides the token. The number of red (blue) boxes varies from 9,8,7,6,3,2, so that the winning odds for a specific color are either high, mediocre or low but never equal.

The practice block runs 5 trials with a fixed order of blue/red ratios and a fixed order of token positions. The order of the two test blocks is counterbalanced by groupnumber. In each condition, participants start with a start capital of 100 points. Each condition runs 36 trials (unless a block is prematurely aborted to too low betting funds), so that each of the four ratios (1/9,2/8,3/7,4/6) is tested 9 times in each condition. Half the time, there are more red boxes. The ratios of the 36 box displays as well as their token positions are presented in a fixed order (the order was pseudo-randomly determined by Millisecond). In about 1/6 of all trials, the better choice leads to a loss (that is the token is hidden under the low-odds color).

In both betting conditions, participants see the 10 red/blue boxes and first select the color of the box that they bet contains the winning token. There is no time pressure for this selection. Then the actual betting procedure starts: in the Ascending condition, participants are presented with five betting amounts that appear in a 'betting box', starting with the lowest possible bet amount and ending with the highest possible bet amount. In the Descending condition, the five amounts decrease from the highest amount possible down to the lowest. The bet amounts are calculated based on a percentage of the current total points that the participant currently owns. In the Ascending condition, the bet amount increases from 5%, 25%, 50%, 75% to 95% of the total points, whereas in the Descending conditions the bet amounts change from 95% down to 5%. Each of the five bet amounts is presented for 5 seconds (and accompanied by a specific beep) before the number changes and participants are asked to click or touch the 'betting box' when it contains the number of points they want to bet. So, if they want to bet a lot of points (95% of their total points), they must wait longer in the Ascending bet condition than in the Descending one. If no bet is selected in time, the last bet is taken as the default one. Once the betting phase has ended, the location of the token is revealed and the betting amount is either added to the total amount (in case, the participant bet on the correct color) or it is subtracted from the total amount.

What it Measures

The Millisecond Gambling Task (MGT) measures decision-making, risk-seeking, and impulsivity under explicit risk conditions

Psychological domains

• Decision-making: Response to potential rewards and losses over time
• Risk-taking: Preference for high-reward/high risk or low-reward/low-risk
• Impulsivity: Preference to take early bets regardless of betting amount ("Action Impulsivity")
• Executive Control: The ability of our prefrontal cortex to override automatic, reward-seeking behavior to execute an exploratory choice

Main Performance Metrics

• Deliberation Time: Time spent on deciding which color to bet on; measure of cognitive processing speed and information gathering
• Proportion Higher Odds Selections: Proportion of times that participant bet on the color with the better odds; measure of quality of decision making
• Mean Risk Percentage: The mean bet amount percentage made for 'better odds choices'; measure of general risk taking
• Risk Adjustment: Difference in mean risk percentages for high win probabilities compared to mediocre ones; measure of sensitivity to winning odds
• Delay Aversion: Difference in bet amount percentage for 'better odds choices' in Descending and Ascending condition; measure of 'action impulsivity'

Psychiatric Conditions

CGT type gambling tasks have been used with the following patient groups:

• Gambling Disorder
• Substance Use Disorders (SUDs)
• Binge Eating Disorder
• Attention-Deficit/Hyperactivity Disorder (ADHD)
• Obsessive-Compulsive Disorder (OCD)
• Schizophrenia

References

Search Google Scholar for peer-reviewed, published research using the Inquisit Millisecond Gambling Task.

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Rogers, R. D., Everitt, B. J., Baldacchino, A., Blackshaw, A. J., Swainson, R., Wynne, K., Baker, N. B., ... Robbins, T. W. (January 01, 1999). Dissociable deficits in the decision-making cognition of chronic amphetamine abusers, opiate abusers, patients with focal damage to prefrontal cortex, and tryptophan-depleted normal volunteers: evidence for monoaminergic mechanisms. Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology, 20, 4, 322-39.

Rahman, S., Sahakian, B. J., Hodges, J. R., Rogers, R. D., & Robbins, T. W. (January 01, 1999). Specific cognitive deficits in mild frontal variant frontotemporal dementia. Brain : a Journal of Neurology, 122, 1469-93.

Mavaddat, N., Kirkpatrick, P. J., Rogers, R. D., & Sahakian, B. J. (January 01, 2000). Deficits in decision-making in patients with aneurysms of the anterior communicating artery. Brain : a Journal of Neurology, 123, 2109-17.

Cools, R., Barker, R. A., Sahakian, B. J., & Robbins, T. W. (January 01, 2003). L-Dopa medication remediates cognitive inflexibility, but increases impulsivity in patients with Parkinson's disease. Neuropsychologia, 41, 11, 1431-41.

Clark, L., Cools, R., & Robbins, T. W. (June 01, 2004). The neuropsychology of ventral prefrontal cortex: Decision-making and reversal learning. Brain and Cognition, 55, 1, 41-53.

Clark, L., Bechara, A., Damasio, H., Aitken, M. R., Sahakian, B. J., & Robbins, T. W. (January 01, 2008). Differential effects of insular and ventromedial prefrontal cortex lesions on risky decision-making. Brain : a Journal of Neurology, 131, 1311-22.

Mochizuki, K., & Funahashi, S. (June 01, 2009). Effect of emotional distracters on cognitive decision-making in Cambridge gambling task. Psychologia, 52, 2, 122-136.

Grant, J. E., Chamberlain, S. R., Schreiber, L., & Odlaug, B. L. (January 01, 2012). Neuropsychological deficits associated with cannabis use in young adults. Drug and Alcohol Dependence, 121, 1-2.