Multivariate data analysis in empirical research

The interpretive benefits of employing multivariate analysis methods on experimental data with more than one dependent variable are described heuristically and illustrated on a set of data from a simply designed experiment in physiological psychology. Multivariate analysis of variance (MANOVA) is performed on the 9 dependent variables contained in the sample data and on the four composites derived from a principal components analysis (PCA) of the variability of the nine. A linear discriminant analysis (LDA) is conducted following both MANOVA results, and 5 methods of determining the “important” dependent variables in the experimental-control group difference are presented and discussed in terms of the data at hand.     

Visual and auditory choice reaction times

Choice reaction times are measured for three values of a priori signal probability with three well-practiced observers. Two sets of data are taken with the only difference being the modality of the reaction signal. In one set of conditions it is auditory, in the other, visual. The auditory reaction times are faster than the visual and in addition several other differences are noted. The latency of the errors and correct responses are nearly equal for the auditory data. Error latencies are nearly 30% faster for the visual data. Non-stationary effects, autocorrelation between successive latencies and non-homogeneous distribution of errors, are clearly evident in the visual data, but are small or non-existent in the auditory data. The data are compared with several models of the choice reaction time process but none of the models is completely adequate.     

Compliance,conversion and the Asch paradigm

120 subjects took part in an Asch type experiment, using a material which was suitable for the measurement of indirect influence. The subjects were given the consistent incorrect response of a source which was either a majority (the response given by 88 per cent of a parent population of college students) or a minority (12 per cent). Part of the subjects were told that the experiment was investigating perceptual illusions and an example of such illusions was given. An authority condition was also introduced: the experimenter himself gave the incorrect response. A control condition did not involve any influence or illusion. The results show that direct influence increases when there is a stronger symbolic social pressure. They also show that an indirect influence may be induced by a numerical majority (provided that the subjects believe that there is an illusion) as well as a numerical minority (provided that an illusion does not invalidate its response). These results underline how important it is to control the exact significance of experimental situations that are supposed to represent the psychological conditions of majority or minority influence.     

Visual perception of motion in depth: Application of a vector model to three-dot motion patterns

The aim of the present study was to identify spatial properties of three-dot motion patterns yielding perceived motion in depth. A proposed vector model analyzed each pattern in terms of common and relative motion components of the moving parts. The dots moved in straight paths in a frontoparallel plane. The Ss reported verbally what they perceived. The common motion did not affect the kénd of perceived event (translation or rotation in depth). Relative motions toward or away from a common point, i.e. concurrent motions, yielded perceived translatory motion in depth. Parallel relative motions toward or away from a common line generally yielded perceived rotation in depth. Complex motion patterns, consisting of concurrent and parallel relative motion components combined, evoked simultaneously perceived translation and rotation in depth under certain phase conditions of the components. Some limitations of the model were discussed and suggestions made to widen its generality.     

THE INFLUENCE OF ALCOHOL ON THE DETECTION OF LIGHT SIGNALS IN DIFFERENT PARTS OF THE VISUAL FIELD

6 subjects performed 12 times each a signal detection task lasting 40 minutes in parallel with a simple tracking task. They reported every 2nd second whether or not a signal was given in any one of 10 widely spaced locations. 0.5 or 1.0 ml alcohol/kg body weight (or no alcohol) was given 35–25 minutes prior to the task. Hit rate ( HR ) covaried with tracking efficiency; FAR was uniformly low. Variation in signal probability had no effect. Alcohol had a strong and uniform effect on 3 "experienced" subjects, reducing HR for all signals and producing a funneling effect, but had little effect on the performance of 3 "inexperienced" subjects. Motivational variables which may account for the individual differences are discussed.     

T × W Completeness

T × W logic is a combination of tense and modal logic for worlds or histories with the same time order. It is the basis for logics of causation, agency and conditionals, and therefore an important tool for philosophical logic. Semantically it has been defined, among others, by R. H. Thomason. Using an operator expressing truth in all worlds, first discussed by C. M. Di Maio and A. Zanardo, an axiomatization is given and its completeness proved via D. Gabbays irreflexivity lemma. Given this lemma the proof is more or less straight forward. At the end an alternative axiomatization is sketched in which Di Maios and Zanardos operator is replaced by a version of actually.