Finally, four-of-a-kind trials were those on which the same stimulus appeared on all four tumblers.
One-of-a-kind trials were those on which the stimulus appearing on the first tumbler was not repeated on any of the other tumblers.
Only four-of-a-kind trials resulted in the delivery of 3-sec access to reward, which was followed by entry into the ITI.
One-of-a-kind, two-of-a-kind, and three-of-a-kind trials resulted in no reward and direct entry into the ITI.
Consistent with the human literature [32], we found that the latency following four-of-a-kind (winning) trials was longer than that following one-of-a-kind, two-of-a-kind, and three-of-a-kind trials, and that the latency following one-of-a-kind, two-of-a-kind, and three-of-a-kind trials was no different.
For the reward related neurons, neural responses to the first two tumblers on two-of-a-kind trials, the first three tumblers on three-of-a-kind trials, and the four tumblers on four-of-a-kind (winning) trials were analyzed together.
Specifically, we looked to see whether a neuron increased or decreased its activity across the first two tumblers on two-of-a-kind trials, across the first three tumblers on three-of-a-kind trials, and across all four tumblers on four-of-a-kind (winning) trials.
Post-hoc Scheffe tests (evaluated at p<.05) were then used to determine if the latency following four-of-a-kind (winning) trials was longer than that following one-of-a-kind, two-of-a-kind, and three-of-a-kind trials, and that the latency following one-of-a-kind, two-of-a-kind, and three-of-a-kind trials was no different.
It is possible that if the frequency of reward was reduced and the frequency of near misses increased (e.g. a greater number of three-of-a-kind trials) the Near-Miss neurons would be better represented.
Two-of-a-kind and three-of-a-kind trials were those in which a stimulus was repeated across the first two and three tumblers, respectively, and then followed by different stimuli on the remaining tumblers.
To compare the response latency to start a new trial after winning (four-of-a-kind) and losing (one-of-a-kind, two-of-a-kind, and three-of-a-kind) trials, a one-way ANOVA with repeated measures across Trial Type (one-of-a-kind vs. two-of-a-kind vs. three-of-a-kind vs. four-of-a-kind) was conducted.
