The Analytic Truth and Falsity of Disjunctions

Disjunctive inferences are difficult. According to the theory of mental models, it is because of the alternative possibilities to which disjunctions refer. Three experiments corroborated further predictions of the mental model theory. Participants judged that disjunctions, such as Either this year is a leap year or it is a common year are true. Given a disjunction such as Either A or B, they tended to evaluate the four cases in its ‘partition’: A and B, A and not‐B, not‐A and B, not‐A and not‐B, as ‘possible’ or ‘impossible’ in ways that bore out the difference between inclusive disjunctions (‘or both’) and exclusive disjunctions (‘but not both’). Knowledge usually concerns what is true, and so when participants judge that a disjunction is false, or contingent, and evaluate the cases in its partition, they depend on inferences that yield predictable errors. They tended to judge that disjunctions, such as follows: Either the food is cold or else it is tepid, but not both, are true, though in fact they could be false. They tended to infer ‘mirror‐image’ evaluations that yield the same possibilities for false disjunctions as those for true disjunctions. The article considers the implications of these results for alternative theories based on classical logic or on the probability calculus.     

Forget about the future: effects of thought suppression on memory for imaginary emotional episodes

Whether intentional suppression of an unpleasant or unwanted memory reduces the ability to recall that memory subsequently is a contested issue in contemporary memory research. Building on findings that similar processes are recruited when individuals remember the past and imagine the future, we measured the effects of thought suppression on memory for imagined future scenarios. Thought suppression reduced the ability to recall emotionally negative scenarios, but not those that were emotionally positive. This finding suggests that intentionally avoiding thoughts about emotionally negative episodes may inhibit representations of those memories, progressively reducing their availability to recall.     

The equivalence of regression models using difference scores and models using separate scores for each informant: implications for the study of informant discrepancies

Research on informant discrepancies has increasingly utilized difference scores. This article demonstrates the statistical equivalence of regression models using difference scores (raw or standardized) and regression models using separate scores for each informant to show that interpretations should be consistent with both models. First, regression equations were used to demonstrate that difference score models are equivalent to models using separate scores for each informant. Second, a hypothesis-driven empirical example (218 mother-child dyads, mean age = 11.5 years, 49% female participants, 49% White, 47% African American) was used to provide an illustration of the equivalence of the 2 models. Implications of the equivalence of models using difference scores and models using separate scores for each informant are discussed in terms of the growing prevalence of an interpretation in the literature of difference score analyses that is inconsistent with results from equivalent separate informant analyses. Differences in the separate predictive ability of informants should be acknowledged as an alternative interpretation of the difference score regression coefficient.     

A comparative analysis of serial and free recall

Multitrial free and serial recall tasks differ both in recall instruction and in presentation order across trials. Waugh (1961) compared these paradigms with an intermediate condition: free recall with constant presentation order. She concluded that differences between free and serial recall were due only to recall instructions, and not to presentation order. The present study reevaluated the relation between free and serial recall, using Waugh's three conditions. By examining recall transitions and the organization of information retained across trials, we conclude that presentation order is an important factor, causing participants to exhibit the same temporal associations in serial recall and in free recall with constant presentation order.     

Individual differences in the effects of spontaneous mimicry on emotional contagion

Two experiments explored the role of mimicry and self-perception processes in emotional contagion. In Study 1, 46 subjects watched two brief film clips depicting an episode of startled fear. In a separate procedure, subjects adopted facial expressions of emotion, and reported whether the expressions had caused them to feel corresponding emotions. Those who reported feeling the emotions were identified as more responsive to self-produced cues for feeling. Subjects who visibly moved to mimic the behavior of the actor were significantly more likely to be those who were more responsive to self-produced cues. In Study 2, 57 subjects watched three film clips depicting happy people. During clips when they inhibited the movements of their faces, subjects reported less happiness than during clips when they moved naturally and were able to mimic, or when they exaggerated their movements. This effect occurred only among subjects who, in a separate procedure, had been identified as more responsive to self-produced cues.The authors would like to thank Paul Ekman, Jerry Ginzburg, and an anonymous reviewer for very helpful suggestions for ways to improve the paper.     

A model theory of induction

Theories of induction in psychology and artificial intelligence assume that the process leads from observation and knowledge to the formulation of linguistic conjectures. This paper proposes instead that the process yields mental models of phenomena. It uses this hypothesis to distinguish between deduction, induction, and creative forms of thought. It shows how models could underlie inductions about specific matters. In the domain of linguistic conjectures, there are many possible inductive generalizations of a conjecture. In the domain of models, however, generalization calls for only a single operation: the addition of information to a model. If the information to be added is inconsistent with the model, then it eliminates the model as false: this operation suffices for all generalizations in a Boolean domain. Otherwise, the information that is added may have effects equivalent (a) to the replacement of an existential quantifier by a universal quantifier, or (b) to the promotion of an existential quantifier from inside to outside the scope of a universal quantifier. The latter operation is novel, and does not seem to have been used in any linguistic theory of induction. Finally, the paper describes a set of constraints on human induction, and outlines the evidence in favor of a model theory of induction.     

A comparison of self-instructional checking procedures for remediating mathematical deficits

We examined the relative effectiveness of three procedures for teaching long multiplication/division to seven adolescents with learning disabilities: no-checking, end-checking, and multi-checking. During training, each subject was taught by modelling and imitation to verbalize self-instructions in the form of a strategy while solving the problems. The relative effects of the checking and no-checking procedures on accuracy and rate of problems completed were examined in an alternating treatments design. The best treatment was then given alone and a reversal was implemented six weeks later, followed by a return to the best treatment during a final phase. Irrespective of the procedure used, the subjects' accuracy improved while the rate of problems completed decreased. These effects were greatest with the multi-checking procedure for six of the seven subjects. Generalization to untaught problems of various levels of complexity occurred under all procedures. Though maintenance effects were seen during the follow-up, accuracy was generally higher and more reliable when the subject's best checking procedure was reinstated. It is suggested that error detection and correction were important for maintaining high levels of accuracy and that these operated differentially in the three procedures to produce the differing levels of accuracy. The role of other factors such as pre-skill knowledge, complexity of the problem and prior reinforcement history are also considered.