Algorithms of adaptation in inductive inference.

We investigate the idea that human concept inference utilizes local adaptive search within a compositional mental theory space. To explore this, we study human judgments in a challenging task that involves actively gathering evidence about a symbolic rule governing the behavior of a simulated environment. Participants learn by performing mini-experiments before making generalizations and explicit guesses about a hidden rule. They then collect additional evidence themselves (Experiment 1) or observe evidence gathered by someone else (Experiment 2) before revising their own generalizations and guesses. In each case, we focus on the relationship between participants' initial and revised guesses about the hidden rule concept. We find an order effect whereby revised guesses are anchored to idiosyncratic elements of the earlier guess. To explain this pattern, we develop a family of process accounts that combine program induction ideas with local (MCMC-like) adaptation mechanisms. A particularly local variant of this adaptive account captures participants' hypothesis revisions better than a range of alternative explanations. We take this as suggestive that people deal with the inherent complexity of concept inference partly through use of local adaptive search in a latent compositional theory space.

Believing does not equal remembering: The effects of social feedback and objective false evidence on belief in occurrence, belief in accuracy, and recollection.

We examined the impact of social feedback and objective false evidence on belief in occurrence, belief in accuracy, and recollection of an autobiographical experience. Participants viewed six virtual scenes (e.g., park) and were tested on their belief/recollection. After 1-week, participants were randomly assigned to four groups. One group received social feedback that one scene was not experienced. A second group received objective false evidence that one of the scenes was not shown. A third group received both social feedback and objective false evidence and the control group did not receive any manipulation. Belief in occurrence dropped considerably in the social feedback group and in the combined group. Also, nonbelieved memories were most likely to occur in participants receiving both social feedback and objective false evidence. We show that social feedback and objective false evidence undermine belief in occurrence, but that they leave belief in accuracy and recollection unaffected.