This page is designed to compare a Monte-Carlo simulation with our computational model. The key idea of this model model is that the relative payoff for different run lengths of trials (e. g., run length of 1 means checking in every trial or 100 %, 2 would be 50 %, 3 would be 33 % and so forth is compared. The simulation and computational model agree very nicely in their predictions.
Simulation
The simulation that can be plotted here generates task sequences and the simulates an agent performing with a stochastic check rate, and assigns corresponding RTs to simulated trials with and without cue checks, assigns gains and losses for simulated correct and incorrect trials, and then summarizes the iteration in the payoff.
Computational Model
The model calculates the payoff for all attentional strategies such that one can visualize the optimality curve. It takes into account the probability of a task switch, p, the gains g per correct trial and losses l for incorrect trials. To compute the relative time cost, individual RTs for trials with and without cue checks are needed. To interpolate over the entire block duration, the duration of the inter-trial-interval and the total block duration are needed.
First, we calculate the probability that the task remains the same at trial \(n\):
$$p_{same}(n) = \frac{1}{2} [1 + (1 - 2p)^n]$$
The expected payoff for a single trial \(n\) without checking:
$$PONC_n = p_{same}(n) g + (1 - p_{same}(n)) l$$
Where \(g\) is gain and \(l\) is loss.
The average payoff over a run of length \(r\) without checking:
$$APONC_r = \frac{1}{r} \sum_{n=1}^{r} PONC_n$$
If a check occurs on the last trial (guaranteeing a win), the average payoff is:
$$APOC_r = \frac{1}{r} (\sum_{n=1}^{r-1} PONC_n + g)$$
We calculate a time-cost multiplier based on RT, ITI, and check duration:
$$CC_r = \frac{RT + ITI + \frac{CT+D}{r}}{RT + ITI}$$
The average payoff of checking is adjusted by this time cost:
$$APOCTA_r = \frac{APOC_r}{CC_r}$$
Finally, we compare the relative payoff of NOT checking vs. checking:
$$PNCC_r = APONC_r - APOCTA_r$$
Decision Policy:
If \(PNCC_r < 0\), the optimal strategy is to check (Cue Fixation).