Gambling near-misses enhance motivation to gamble and recruit win-related brain circuitry

Abstract

"Near-miss" events, where unsuccessful outcomes are proximal to the jackpot, increase gambling propensity and may be associated with the addictiveness of gambling, but little is known about the neurocognitive mechanisms that underlie their potency. Using a simplified slot machine task, we measured behavioral and neural responses to gambling outcomes. Compared to "full-misses," near-misses were experienced as less pleasant, but increased desire to play. This effect was restricted to trials where the subject had personal control over arranging their gamble. Near-miss outcomes recruited striatal and insula circuitry that also responded to monetary wins; in addition, near-miss-related activity in the rostral anterior cingulate cortex varied as a function of personal control. Insula activity to near-misses correlated with self-report ratings as well as a questionnaire measure of gambling propensity. These data indicate that near-misses invigorate gambling through the anomalous recruitment of reward circuitry, despite the objective lack of monetary reinforcement on these trials.

Figure 1

Screen Display for the Slot Machine Task The slot machine task displayed two reels, a payline and a box displaying current earnings. Both reels displayed the same six icons. Each trial commenced with a selection phase (duration 5 s), where either the participant or the computer selected the “play icon” on the left-hand reel. The right-hand reel then spun for a variable anticipation phase (duration 2.8–6 s), decelerating to a standstill. In the outcome phase (duration 4 s), if the play icon on the right-hand reel stopped in the payline (i.e., was aligned with the chosen play icon on the left-hand reel), the participant won £0.50. Other outcomes yielded no win; it was not possible for the participant to lose money. Trials where the right-hand reel reached a standstill one position from the payline (either above or below) were classified as near-misses, and trials where the right-hand reel stopped more than one position from the payline were classified as full-misses. During the selection phase, participants performed a pseudorandom sequence of participant-chosen (white background) and computer-chosen (black background) trials. On participant-chosen trials, the subject was able to rotate the left-hand reel and select a play icon by moving it around to the payline. On computer-chosen trials, the computer would rotate the left-hand reel until one play icon was highlighted on the payline; the subject was required to confirm selection with a button press to ensure adequate attention.

Figure 2

Subjective Ratings on the Slot Machine Task Ratings for each subject were standardized based on the individual's mean and standard deviation for that rating, given the variability in anchoring across subjects. (A) Ratings of “How do you rate your chances of winning?” were significantly higher on participant-chosen trials compared to computer-chosen trials (t₃₉ = 5.09, p < 0.001). (B) Ratings of “How much do you want to continue to play the game?” on near-miss and full-miss outcomes. The “near-miss effect” (increased desire to play after near-misses) was restricted to trials where the subject had personal control over the gamble; near-misses selected by the computer significantly reduced desire to play. Error bars indicate standard error of the mean.

Figure 3

Neural Activity to Winning and Near-Miss Outcomes (A) Neural responses to monetary wins compared to all non-wins, modeled to the onset of the outcome phase. Suprathreshold voxels (p < 0.05 corrected for multiple comparisons) are displayed across 5 axial sections on the ch2bet template, using MRIcron software (http://www.sph.sc.edu/comd/rorden/mricron/). There was significant win-related activity in the ventral putamen (left: −14 10 −2; right 16 4 −12), anterior insula (left: −36 18 −4; right 28 16 −10), midbrain (−6 −20 −14) and rostral anterior cingulate cortex (−4 32 6) (see Table S3). (B) Neural responses to near-miss outcomes compared to full-miss outcomes, using a mask of win-related activity (mask thresholded at p_FWE-corr < 0.05). The contrast map has been thresholded at the lower level of p < 0.001 uncorrected to illustrate the anatomical extent of the clusters. Near-misses were associated with significant activity (p_FWE-corr < 0.05) in the bilateral ventral putamen (left: −8 4 −2; right 12 2 −2) and right anterior insula (32 18 0).

Figure 4

Near Miss by Control Interaction in Rostral ACC (A) The interactive effect of near-misses and personal control was associated with signal change in the rostral anterior cingulate cortex (rACC, Brodmann Area 24). The contrast image shown was restricted to near-miss outcomes that passed through the payline, compared to full-misses, using a mask of win-related activity (mask thresholded at p_FWE-corr < 0.05). For display purposes, the contrast map is thresholded at p < 0.001 uncorrected. (B) Extracted signal change from this cluster (averaged across all suprathreshold voxels using Marsbar) reveals that rACC activity was greater for near-misses (compared to full-misses) on participant-chosen trials (p = 0.005) but was lower for near-misses (compared to full-misses) on computer-chosen trials (p = 0.058). Error bars indicate standard error of the mean.

Figure 5

Insula Activation to Near-Misses Correlated with Trait Gambling Propensity and the Subjective Effect of Near-Misses (A) A trait measure of the susceptibility to gambling biases (the gambling-related cognitions scale; GRCS) predicted near-miss-related neural activity (contrast of near-misses minus full-misses) in the anterior insula/caudolateral orbitofrontal cortex (Brodmann Area 47). An SPM5 regression of near-miss-related activity onto GRCS total score, using a mask of win-related activity, revealed a single significant cluster in the left anterior insula (x, y, z = −42, 18, −10, z = 3.98, p_FWE-corr = 0.018), with extracted signal change displayed on the right hand side. For display purposes, the regression map is thresholded at p < 0.005 uncorrected. (B) Near-miss related activity in the anterior insula (Brodmann Area 13) was also significantly correlated with the subjective effects of near-miss outcomes on a rating of “How much do you want to continue to play the game?” The SPM5 regression map reveals a cluster in the right anterior insula (x, y, z = 30, 16, −10, z = 3.24, p_unc = 0.001), with extracted signal change displayed on the right hand side. For display purposes, the regression map is thresholded at p < 0.005 uncorrected.