How effectively can groups of people make yes-or-no decisions? To answer this question, we used signal-detection theory to model the behavior of groups of human participants in a visual detection task. The detection model specifies how performance depends on the group's size, the competence of the members, the correlation among members' judgments, the constraints on member interaction, and the group's decision rule. The model also allows specification of performance efficiency, which is a measure of how closely a group's performance matches the statistically optimal group. The performance of our groups was consistent with the theoretical predictions, but efficiency decreased as group size increased. This result was attributable to a decrease in the effort that members gave to their individual tasks rather than to an inefficiency in combining the information in the members' judgments.

The development and psychometric properties of the Memory Self-Efficacy Questionnaire (MSEQ), a self-report measure of memory ability (Self-Efficacy Level) and confidence (Self-Efficacy Strength), are described. The MSEQ was rationally constructed using 50 memory items with face and content validity. The MSEQ and its alternate versions were examined in three experiments with younger and older adult samples. Satisfactory estimates of internal consistency and test-retest stability were obtained. Canonical correlation analyses provided preliminary support for the MSEQ's criterion and construct validity. Although additional psychometric work is needed, this initial investigation of the MSEQ suggests that it may be a useful tool for research on memory self-evaluation in adult age groups. Reliability and validity are strong, the questionnaire shows expected adult age differences in self-evaluation, and the theoretical framework of self-efficacy provides useful hypotheses regarding developmental changes and individual differences in self-evaluation.Current investigations of memory and aging have moved beyond simplistic descriptions of deficits attributed to chronological age toward an integration of the relevant task, context, and person variables that influence memory performance (e.g.,

This article is an integrative review of empirical studies of cognitive self-efficacy from childhood through old age. Issues of definition and measurement are addressed and the relation of self-efficacy to personal mastery is evaluated. Research on academic achievement in children and adolescents, complex decision-making in young adults, and memory and intellectual functioning in older adults supports a variety of theoretically driven hypotheses regarding the sources and effects of self-efficacy. Percepts of self-efficacy are based on a variety of sources of information, including personal mastery and perceived control beliefs. Self-efficacy has predictable effects on a variety of task engagement variables (e.g. persistence, effort, goal setting, strategy usage, chioce) that mediate the relationship between self-efficacy and performance. Generalisations regarding the applicability of self-efficacy to understanding cognitive development across the life span are discussed in terms of age-relevant domains and it is argued that a life span treatment of self-efficacy development is particularly compelling because both life span theory and self-efficacy theory emphasise domain specificity.

Gerontologists have long been concerned with the impact of individual-difference factors on memory. This study used a large sample (N = 2,495) of adult volunteers aged 18 to 90 years to determine if a set of individual-difference variables--vocabulary, education, depression, gender, marital status, and employment status--mediates the effects of aging on a wide range of laboratory-analogue tests of everyday memory. The data indicated that age was consistently the most significant predictor of memory performance, followed by vocabulary and gender. Vocabulary totally mediated age effects on a prose memory measure, and partial mediation of aging effects--primarily by vocabulary and gender--was observed on 5 other memory tests. These data suggest that when health samples of volunteers serve as research subjects, these individual differences can affect some memory test scores, but age remains the best overall predictor of memory performance.

Some group decisions require a two-thirds or three-quarters majority of the people voting; others require only a simple majority. Does the accuracy of a group's decision making depend on which majority rule is used? A signal detection theory analysis was used to answer this question. Each member of a group was presented with a noisy display of either a signal or a nonsignal, and then each member cast a yes or no vote for the existence of a signal. The group decision was determined by a majority rule of the members' votes. Normative groups and groups of 5 or 7 people exhibited the same behavior: Performance was best when the group used a simple-majority rule and decreased when the group used more stringent rules. The worst performance was produced by a unanimous rule. Some group members adopted more liberal response criteria when the majority rule was made more stringent.