Study title

United Kingdom

Individual

This was an experimental study, in which participants did a task on a computer that was custom-developed to address the main questions described above. Design and procedure: Each participant completed a fixed condition and a free condition. We varied location cue reliability between subjects, by changing the width of the distribution from which the dot location cues were sampled from sigma=12mm to sigma=28mm (see below for details). Most adults did both cue reliability conditions, but we only analysed the first cue reliability condition they took part in. All subject completed the free condition, to measure sampling choices, and the fixed condition to model the ideal strategy that should be used to maximise score in the free condition (see below for details).In the free conditions participants sampled probabilistic location cues (dots) drawn from a bivariate Gaussian distribution with sigma=12 or sigma=28, centred on a target (max Ndots was 20). They bought between 1 to 20 dots by pressing space bar, with the score won for a hit depreciating with 1 point for each dot (starting from 20 points). Because the middle of the dot-cues is more likely to overlap with the target/distribution mean as the number of dots increases (as variance around this location follows sigma/sqrt(Ndots)), sampling more dots increased the chance of locating the target. However, purchasing more dots also reduced the value of the target, so participants had to trade-off the benefits of more information against the cost. Once the participant felt they had bought a sufficient numbers of dots, they placed the cursor on a touchscreen in the estimated mean location of all the dots to find the target. They then were able to adjust their response until they confirmed their choice by pressing enter, upon which they got feedback about whether they had hit the target, and about their score. Each participant completed 100 trials of this condition. In the fixed conditions, the design was identical except that rather than purchasing a number of dots of their choice, participants were presented with a fixed number of dots on each trial, and then located the mean of the dots to find the target following the same procedure as in the free condition. This condition was used to model the ideal strategy in the free condition; Specifically we used it to estimate for each individual, the hit probability for a given Ndots, and multiplied this by the points that could be won for this ndots to obtain the expected gain (hit probability x value) for that given Ndots. The ideal strategy is to sample the Ndots with the highest expected outcome. Each participant completed 25 trials with a fixed number of dots. Most children were presented with Ndots = [2 3 7 15]. Some adults were presented with all Ndots in this condition.