Proportion Of Judgments Research Articles

Anomalies in the Judgment of Statistical Association: Fallacies Based on Unidirectional Independence, Shifting Dependence, and Conjunction

An experiment was performed in which subjects, trained in basic probability, were asked to judge the likelihood of one trait (A), e.g., intelligence, given another (B), e.g., submissiveness, relative to p(A) or p(A|B) They also ranked p(A), p(B), and p(A∩B) for relative size. A substantial proportion of judgments violated the laws of probability by endorsing relationships that implied independence was a function of the direction of association, i.e., p(A|B) = p(A) [or p(A|B̄)], but p(B|A)≠p(B) [or p(B|A)]. Further, many subjects endorsed relationships that implied independence in one direction changed to dependence with change in statistical comparison, i.e., p(A|B) = p(A) [or p(A|B̄)], but p(A|B)≠p(A|B̄) [or p(A)]. These violations of the laws of probability were correlated with each other. A tendency to perceive a positive relationship between two traits correlated with a tendency to commit the fallacy of conjunction. It was concluded that individuals made probabilistic judgments which did not incorporate understanding of probabilistic relationships between events. Also the departures from correct probabilistic reasoning could not be accounted for very well by confusion of causal explanations with diagnosticity of the traits.

The Golden Section and Structure of Self-Concepts

It was hypothesized that, when subjects form impressions of a person whom they have just met for the first time, the mean proportion of perceived differences between self and other will be approximately 0.368. Undergraduates, 15 women and 15 men, were asked to categorize a new acquaintance, following a brief conversation with him, on 22 bipolar dimensions elicited from themselves. They also categorized themselves on the same dimensions. The mean proportion of judgments of unlike-self of the new acquaintance was 0.364, which is quite close to the predicted value and consistent with the results of related experiments. Perhaps differences between self and others define the contours of the self as "figure" against a diffuse background of similarities.

The preschool child's perception of adult approval in "nondirective" statements.

Twenty children of nursery school age participated in a study of adult approval/ disapproval as conveyed by nondirective statements relating to play aggression. Though all sentences were tape recorded in a neutral voice, 10 of 15 conveyed disapproval in a significant proportion of judgments. All statements explicitly mentioning aggression were judged disapproving. It was concluded that nondirective play therapists must convey acceptance through other modes in order to avoid suppressing aggressive play.

A FURTHER STUDY OF ESTIMATING AVERAGES

An investigation is described of the types of averaging response made to several volues of a variable when these nre presented symbolically or graphically. Symbolic information was presented to subjects on small white cards on which were typed either 10 or 20 two-digit numbers. Graphical information was presented as 10 or 20 points on inch ruled tenths graph paper. Sets of data differed according to whether they were normally or skew distributed about the arithmetic mean value, and in the extent of scatter about the mean. The results confirmed previous work in showing that error of judgment increased as scatter increased, and to a greater extent with symbolic than "with grnphical material. Error was also greater with skew than with normal information. Comparison between the results obtained with the two types of distribution showed that the previously reported finding that error also increased with increasing amount of information was incorrect and was duo to inadequate experimental control of scatter for different amounts of information. Analysis of individual performances showed that subjects' responses differed in type and that their introspective reports related to their performance. In particular the proportion of judgments which could be classed as of ' arithmetic mean ' type varied significantly with the methods described. Further experiments are suggested to try to discover which of two possible models of mental averaging is correct and why error increased with increased scatter in the information.