Disjunction and conjunction fallacies in episodic memory

Does context recollection depend on the base-rate of contextual features?

Episodic recollection is defined by the re-experiencing of contextual and target details of a past event. The base-rate dependency hypothesis assumes that the retrieval of one contextual feature from an integrated episodic trace cues the retrieval of another associated feature, and that the more often a particular configuration of features occurs, the more effective this mutual cueing will be. Alternatively, the conditional probability of one feature given another feature may be neglected in memory for contextual features since they are not directly bound to one another. Three conjoint recognition experiments investigated whether memory for context is sensitive to the base-rates of features. Participants studied frequent versus infrequent configurations of features and, during the test, they were asked to recognise one of these features with (vs. without) another feature reinstated. The results showed that the context recollection parameter, representing the re-experience of contextual features in the dual-recollection model, was higher for frequent than infrequent feature configurations only when the binding of feature information was made easier and the differences in the base-rates were extreme, otherwise no difference was found. Similarly, base-rates of features influenced response guessing only in the condition with salient differences in base-rates. The Bayes factor analyses showed that the evidence from two of our experiments favoured the base-rate neglect hypothesis over the base-rate dependency hypothesis; the opposite result was obtained in the third experiment, but only when high base-rate disproportion and facilitated feature binding conditions were used.

Deep memory distortions

Deep distortions are a new family of memory biases that comprise one of the two basic varieties of false memory. The first and older variety, surface distortions, are specific item or source memories that are erroneous because the events did not happen. The new variety, deep distortions, are emergent properties of multiple specific memories. They are relations among such memories that are false because they violate objective logical rules that real-world events must obey. I discuss four deep distortions for which substantial data have accumulated: overdistribution, super-overdistribution, non-additivity, and impossible conjunctions. These phenomena violate four axioms of classical probability (numerical bound, universal event, additivity, and countable additivity) and two rules that follow from them (empty set and monotonicity). Their psychological significance lies in four facts about them: (a) They demonstrate that although events in the real world are compensatory, our memories of them are not; (b) they establish that we persistently over remember experience; (c) they reveal that surface distortions are by-products of deep distortions; and (d) they pose the theoretical conundrum of how the structure of memory could so thoroughly misrepresent the objective structure of the events we are remembering.

Deep distortion

Conventional false memories recount events that either did not happen (item errors) or that happened in a different context (source errors). Fuzzy-trace theory predicts deeper anomalies that lie behind conventional false memories. These deep distortions are structural irregularities in the ways that specific recountings are related to each other or to some objective standard (e.g., the 0 and 1 limits of probability). I discuss five deep distortions for which substantial data have accumulated: overdistribution, non-additivity, conjunction illusions, non-compensation, and super-overdistribution. Together, these phenomena violate the disjunction and additivity axioms of probability, as well as the law of the excluded middle. The theoretical problem they pose is to explain how valid representations of our experience produce memory regularities that violate our experience in the most fundamental ways.

The base rate neglect in episodic memory

The main objective of the present research was, for the first time, to assess a potential similarity in the representational bases for the base rate neglect in memory versus conditional probability judgment. Participants learned target and filler words, each of which was presented on a separate list (List 1 or List 2) and in a distinct colour (red or blue), with a manipulation of different base rates for these list and colour categories. During recognition tests, participants made prior and posterior episodic judgments (e.g., "What colour was the word?", "Given that the word was in red, on which list was the word?") on the target words, which respectively parallel independent and conditional probability assessments that figure in Bayes' theorem. The results implied that biased prior and posterior judgments presumably cause the base rate neglect, inasmuch as the prior cue of a low (high) base rate is likely to lead to a bias toward retrieving high (low) base rate posterior evidence. There was also a finding showing that memory analogues of probability estimates reflect the base rate neglect in both low and high base rate categories, but is presumably stronger with posterior judgment of Colour|List than List|Colour relative to the high base rate category.