Do fears summate?—III

The primary purpose of this investigation was to learn whether fears summate. Thirty Ss who reported and displayed fear in response to a snake and to a spider were shown each stimulus separately and then both stimuli simultaneously, in order to see if their fear responses would summate. They did, overall; however, if Stimulus 1 provoked greater fear than Stimulus 2, the simultaneous presentation of both stimuli was followed by a subtraction. Summation occurred when the second stimulus produced a larger fear response than the first stimulus, and the two were then presented simultaneously.     

A simple method for determining the functional independence of two or more fears—IV

A rationale for a simple method for determining the inter-relatedness of two discrete fears was developed and subjected to experimental test. A system for making such distinctions proved to be satisfactory, but we found no relationship between the person's own estimation of the similarity of the two fears and the index of independence that was derived experimentally. Possible uses of the method are suggested.     

The effects of perceptual set on the shape and apparent depth of subjective contours

Two experiments showed the influence of perceptual set on the perception of subjective contours. In the first, the perceived shape of a subjective-contour figure (a minimal version of the Ehrenstein configuration) was varied by altering the observer’s viewing set. The second experiment showed that apparent depth emerged in subjective-contour figures when observers were set to perceive the illusory contours.     

The experimental analysis of agoraphobia

A concerted move towards the use of experimental analyses is proposed. It is suggested that our understanding of agoraphobia can best be advanced by taking this step. The argument in support of such a move is illustrated and developed in respect of the role of safety signals in maintaining and influencing agoraphobic behaviour. A detailed analysis is given of the factors postulated to determine the strength of safety signals, and the complex inter-relations between fear and safety are examined.     

A comparison of five methods of illusion measurement

The relative efficiency of five techniques of illusion measurement were tested on parametric variations of the Mueller-Lyer and Ebbinghaus figures. The methods of average error, reproduction, and selection from a graded series all showed significant effects of configurational variations. The subjective scaling techniques each failed to measure adequately changes in illusion magnitude for one illusion configuration. The suitability of the tested measures for group administration is also discussed.     

Similarity judgments of line length

Nine Ss judged similarity of pairs of lines on a scale from 0 to 100, and 14 Ss made magnitude estimations of similarity of pairs of lines. The two scales of similarity were linearly related. Scale values for subjective length were obtained in one dimension using a nonmetric multidimensional analysis. Subjective length was found to be logarithmically related to objective length, and similarity was found to be an exponential