Gösta Ekman

Discriminal Sensitivity on the Subjective Continuum

Abstract 1. (1) It is pointed out that the relation between discriminal sensitivity and perceived intensity in the subjective dimension is an important problem which has attracted too little attention. There seems to be no single investigation directly centering on this question. 2. (2) A method is developed for investigating this relation. It is essentially a graphic procedure for differentiating R with respect to S in order to make possible a computation of discriminal dispersions or related measures in terms of R. 3. (3) The method is applied to a fictious numerical example. 4. (4) The same method is applied to published experimental data. It is found that the difference limen is an increasing linear function of intensity in the case of subjective weight, and an increasing, definitely non-linear function in the case of subjective salt intensity. 5. (5) There is indirect evidence that the difference limen in subjective units is constant in the case of brightness and pitch, but is an increasing function of intensity in the case of loudness. 6. (6) The case of qualitative or inter-dimensional variation is discussed. There is indirect evidence that subjective sensitivity is constant along the curvilinear continuum in the multidimensional subjective space of hue. 7. (7) An hypothesis advanced by Stevens and collaborators is contradicted by brightness data but supported by color data. 8. (8) Relations between sensitivity and position in the subjective continuum may possible be ascribed to central processes, which makes them more promising objects of investigation than conventional psychophysical relations which also depend on highly specific peripheral factors.

Effects of alcohol intake on subjective and objective variables over a five-hour period

SummaryEight male subjects were studied during a five-hour period following a single dose of 0.55 g alcohol per kg body weight. The main variables of the experiment were a) blood alcohol concentration, b) self-estimated degree of intoxication, and c) observed degree of intoxication. The subjective scales were obtained by the method of magnitude estimation. The two curves representing self-estimated and observed degree of intoxication were in very close agreement; in a general way they also followed the blood alcohol concentration curve, although certain systematic deviations were found. In addition, d) self-estimates of certain mood variables were obtained, and e) two objective performance tests were administered. Nearly all curves obtained in the experiment showed a peak about 30–40 min after alcohol intake. The subjective variables appeared to be more affected by alcohol than the performance variables.

Individual psychophysical functions for 28 odorants

Individual scales of odor intensity were obtained for 28 different chemical compounds by the method of magnitude estimation. Eleven Ss participated in an experiment with 196 olfactory stimuli which differed in both quality and intensity. It was found (1) that power functions described the relationship between partial vapor pressure of the odorants and their subjective odor intensity for all Ss, (2) that all exponents were less than one but varied greatly between Ss, (3) that consistent intraindividual differences in the exponents of different odorants exist, and (4) that these are attributable to perceptual differences rather than to response bias.

Subjective and objective effects of alcohol as functions of dosage and time

SummaryEight male subjects were studied during a five-hour period following three different doses of a) 0.33, b) 0.44, and c) 0.66 g alcohol per kg body weight.The main dependent variables of the investigation were 1. blood alcohol concentration, 2. self-estimated degree of intoxication, and 3. observed degree of intoxication. The subjective scales were obtained by the method of magnitude estimation. Corresponding curves of self-estimated and observed degree of intoxication were in very close agreement. In most respects the subjective estimation curves also showed a far-reaching agreement with the corresponding blood alcohol curves: a fast intitial growth followed by an essentially linear decline. The rate of decline of the subjective curves was, however, much faster.In addition to these principal data, 4. self-estimates of certain mood variables were obtained, and 5. two objective performance tests were administered. Nearly all curves obtained in the experiments showed a maximal effect about 30–50 min after alcohol intake. The subjective variables, and particularly those related to general intoxication, were on the whole more affected by alcohol than were the performance variables.The results of the present investigation with three doses of alcohol substantiate and widen the conclusions based on a previous study with a single moderate dose.

A mechanism of subjective similarity

SUMMARYThe mechanism of perception of similarity in the dimension of pitch was investigated. Similarity estimates were obtained and a pitch scale was constructed. It was shown that subjective similarity between two tones of equal loudness is equal to the ratio between the lower pitch and the average of the two pitch values. This relation is in a general agreement with Helsons concept of adaption level.

A direct method for multidimensional ratio scaling

A generalization of direct ratio scaling methods to multidimensional ratio scaling is described. This method requires an observer to report the proportion of a standard percept that is contained in a given percept and vice versa. The method was developed to meet requirements for experimentation in such areas as color vision, gustation, and olfaction.

Emotional reaction to past and future events as a function of temporal distance

Abstract In three experiments with 30 Ss, imagined past and future events were used as stimuli. Scales were constructed by the ratio estimation method for (a) subjective temporal distance and (b) emotional reaction to the events. It was found (1) that subjective temporal distance was a power function of chronological distance, (2) that emotional reaction to past events could be described as an exponential function of subjective temporal distance; a simple relation thus exists between the two psychological variables, whereas emotional reaction is related in a more complicated way to the objective variable, and (3) that emotional reaction to future events could be described about as well by a power function as by an exponential function of both subjective and objective temporal distance.

A PSYCHOPHYSICAL STUDY OF CARTOGRAPHIC SYMBOLS

Abstract : In two experiments the subjective volume of certain cartographic symbols was studied by the method of magnitude estimation. The stimulus material consisted of several sets of cubcl. illus. table, 12 refs. (Technical (Scientific) note no. 6) (Contract AF 61(052)300) (AFOSR-1247)Unclassified report DESCRIPTORS: *Visual perception, Perception, Measurement, Map reading. Open-ended Terms: Psychophysics. In two experiments the subjective volume of certain cartographic symbols was studied by the method of magnitude estimation. The stimulus material consisted of several sets of cubes and spheres, drawn with perspective and shadow. The total range of stimulus volume was 1:3,500. Psychophysical power functions yielded a good fit to all experimental data. The exponents varied from 0.56 to 0.82, most of them being close to the average value, 0.69. The results substantiate the tentative conclusion from a previous study, according to which volume estimates in the case of small projected solids essentially reflect perception of area, and this conclusion is further confirmed by a third experiment designed to throw additional light on this particular question. (Author)

Threshold values and the psychophysical function in brightness vision

Abstract Three experiments involving threshold measurement and brightness scaling were conducted with ten dark-adapted subjects. It was demonstrated (1) that the experimentally determined absolute threshold rises with the level of stimulation prevailing in the particular experiment, (2) that threshold values extrapolated from the psychophysical brightness function agree closely with thresholds experimentally determined under proper conditions of stimulation. Finally, it was shown (3) that the psychophysical brightness function is approximately linear for low luminance levels, and this unexpected finding was supported by a re-analysis of data reported by Jameson.

Subjective Geographic Distance: A Multidimensional Comparison.

The interdistances between thirteen places situated in different parts of the world were estimated by 60 subjects. The estimates were analysed by Kruskals multidimensional technique and, after a cosine transformation, by factor analysis. It was found that both methods yielded the same three-dimensional solution. Also a two-dimensional configuration could describe the data, and it was shown that this configuration contained representations of unidimensional ratings obtained in other studies.