On the number of significant findings to be expected by chance

When multiple significance tests are computed, a certain number of significant findings will emerge simply because of chance fluctuations. In the present paper, some factors affecting the number of nominally significant results are elaborated and a general method is suggested which permits unbiased inference as to the significance of a set of findings,as a set. The method advocated employs a high speed computer to generate empirically a sampling distribution tailormade to a particular data matrix. The method is illustrated in the case of dichotomous response to inventory items, where it is found that the statistical model still often used as a basis for estimation is overly conservative. Some problems in the application of the method are discussed.This investigation, part of a larger research project, was supported primarily by research grant M-1078 from the National Institute of Mental Health of the United States Public Health Service. Gratitude is also extended to the National Science Foundation for making available research time on the IBM Model 701 computer. The present paper has benefited greatly from the comments on an earlier version offered by John Tukey and an editor ofPsychometrika.     

Sex differences in duration judgments: A meta-analytic review

We quantitatively reviewed human sex differences in the magnitude and variability of duration judgments. Data from 4,794 females and 4,688 males yielded 87 effect size estimates of magnitude and 28 of variability. The overall sex difference in duration judgment magnitude was small but statistically significant. It was moderated by whether study participants knew in advance (prospective paradigm) or only later (retrospective paradigm) that they would be required to judge duration. Although prospective judgments showed no overall sex effect, some levels of moderator variables showed a small but statistically significant effect. Retrospective judgments showed a larger subjective-to-objective duration ratio for females than for males, and several variables moderated this effect. Females' judgments also showed more intersubject variability than did males' judgments. Relative to males, females sustain attention to time more in the prospective paradigm and have better episodic memory in the retrospective paradigm.     

The role of ego-control, ego-resiliency, and IQ in delay of gratification in adolescence

The delay-of-gratification behavior of 104 14-year-old Ss (54 girls and 50 boys) was assessed in an experiment in which each subject chose between immediate monetary payment and larger, delayed payment on 5 occasions. Personality data were obtained on these adolescents in the form of California Adult Q-Set ratings made by several research examiners who were blind to the subjects' delay behavior. The number of delayed payments chosen was strongly correlated with these personality ratings, within both sexes. Ss who exhibited the most delay of gratification tended to be independently described as responsible, productive, ethically consistent, interested in intellectual matters, and overly controlled. They tended not to be described as unable to delay gratification, rebellious, unpredictable, self-indulgent, or hostile. Delay behavior in both sexes was also correlated positively with IQ and with Q-sort-derived indexes of ego resiliency and ego control. The relationship between ego control and delay behavior was particularly strong after both IQ and ego resiliency were partialled. These results were interpreted as reflecting the fundamental importance of both cognitive skillfulness and impulse control for adaptive delay behavior in situations that contain strong motivational inducements.     

Interfering with memory for faces: The cost of doing two things at once

We inferred the processes critical for episodic retrieval of faces by measuring susceptibility to memory interference from different distracting tasks. Experiment 1 examined recognition of studied faces under full attention (FA) or each of two divided attention (DA) conditions requiring concurrent decisions to auditorily presented letters. Memory was disrupted in both DA relative to FA conditions, a result contrary to a material-specific account of interference effects. Experiment 2 investigated whether the magnitude of interference depended on competition between concurrent tasks for common processing resources. Studied faces were presented either upright (configurally processed) or inverted (featurally processed). Recognition was completed under FA, or DA with one of two face-based distracting tasks requiring either featural or configural processing. We found an interaction: memory for upright faces was lower under DA when the distracting task required configural than featural processing, while the reverse was true for memory of inverted faces. Across experiments, the magnitude of memory interference was similar (a 19% or 20% decline from FA) regardless of whether the materials in the distracting task overlapped with the to-be-remembered information. Importantly, interference was significantly larger (42%) when the processing demands of the distracting and target retrieval task overlapped, suggesting a processing-specific account of memory interference.