The onset of uncertainty facilitates the learning of new associations by increasing attention to cues

Past research in animals has suggested that attention is distributed to exploit known relationships between stimuli and explore stimuli whose consequences are uncertain. While there is strong support for exploitative attention and its effects on learning in humans, the evidence for exploratory attention is less well developed. Two experiments examined whether preferential allocation of attention (as measured by eye-gaze) to cues associated with uncertainty leads to more rapid learning of new associations involving these cues in the future. In each experiment, participants first learned about compounds containing one predictive cue and one nonpredictive cue. The level of uncertainty during this first stage of training was also manipulated: cue-outcome relationships were either deterministic (certain) or probabilistic (uncertain). In a second stage, new cue-outcome relationships were trained and the uncertainty of these relationships could be resolved by learning about the previously nonpredictive cues. As a result of the manipulation of uncertainty in the first stage, some participants experienced a sudden onset of uncertainty at the start of this second stage, while others experienced a stable level of uncertainty throughout the experiment. Experiment 1 showed that the former learned novel cue-outcome associations faster than participants for whom uncertainty was constant. Furthermore, participants experiencing unexpected uncertainty showed a greater increase in attention to cues in Stage 2. Extending the training stage in Experiment 2 resulted in a larger difference in rate of learning between conditions in stage 2. We argue that this represents evidence for an effect of exploratory attention on rate of learning in humans.