The perception of foreground and background as derived from structural information theory

Subjects were instructed to order stimuli, consisting of a white and a black part, in accordance with the perceived foreground-strength of the white (or black) part. It appeared that this task can be carried out consistently. The order is explained on the basis of Structural Information Theory. It is argued that this task involves central processes, and that the strength depends on the preference for an interpretation, in which the white (black) part is a foreground on a black (white) background, with respect to the opposed interpretation in which the white (black) part is the background and the black (white) part is foreground.     

Visually perceived motion in depth resulting from proximal changes. I

According to a model for form and motion perception proposed by Johansson (1964), every two-dimensional change in the proximal stimulation is projected out as a motion in depth. The amount of perceived depth motion can then be predicted from the projective relationship between the proximal change and the projected motion. This prediction was tested in a series of experiments by using squares that continuously changed their sizes as stimuli, and measuring perceived distance of motion in depth. The obtained relationship between perceived and predicted distance of motion was curvilinear for all Ss. Furthermore, the majority of the Ss underestimated the motion systematically, the remainder overestimated it. Thus, the prediction given in the model could not be verified. However, an alternative projective relation based on the assumption that a fixed proportion of the change is not projected out as a motion but perceived as a change of size agreed quite well with the data, both with distance judgments and with judgments of perceived change of size.     

Adaptation to field displacement during head movement unrelated to the constancy of visual direction

Adaptation to vertical field displacements dependent on head turning about a vertical axis was demonstrated under two conditions, rapid training with 100 head movements and 1-h-long training with continuous head turning. The effect of rapid training was measured with the slant estimation method. Adaptation after the longer training was ascertained by comparing the uncertainty ranges for apparent target immobility before and after the adaptation period. Adaptation to field displacements in directions parallel to the plane of the head rotation obtained under corresponding conditions was also measured and found to be somewhat greater than adaptation to vertical field displacements. The result of work by Wallach and Frey that adaptation to field displacement in the direction with the head rotation is greater than to displacement against it was corroborated. While the previous result had, been obtained with rapid adaptation and with the slant estimation method, we confirmed it with 1-h training and by measuring the uncertainty ranges before and after the adaptation period.     

EFFECTS OF CONTINGENCYAND CONTRAST CONTEXTS ON THE COGNITION OF WORDS: A study of stereoscopic rivalry

R ommetveit , R., T och , H. & S vendsen , D. Effects of contingency and contrast contexts on the cognition of words. A study of stereoscopic rivalry. Scad r. Psychol ., 1968, 9, 138–144.—Two typographically very similar words (like 'hell' and 'tell') were presented in a binocular rivalry situation, each appearing after a contrast context (e.g. 'heaven') or a contingency context (e.g. 'devil') had been presented to both eyes. Context effect was then assessed in terms of the frequency with which the context-relevant word was reported as seen. The effect of contrast compared with contingency context was weak when context and test words were presented consecutively, but strong when the context stimulus appeared above the rivalry pair on the same stereogram.     

Semantische Faktoren beim Behalten der Verneinung von Sätzen

Zusammenfassung Es wurde der Einfluß der Faktoren semantische Implikation und Belebtheit des Subjekts auf die Speicherung der Verneinungsformen Subjektverneinung (SV), Prädikatsverneinung (PV) und Objektverneinung (OV) untersucht. Die Analyse der Befunde ergab, daß die Verneinungsformen SV, PV und OV unterschiedlich gut gespeichert werden und die beiden Variablen semantische Implikation und Belebtheit des Subjekts die Speicherung dieser Negationsformen differentiell beeinflussen.

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Semantic factors in storing negated sentences

Summary The influence of the factors semantic implication and animateness of the subject of the sentence upon the recall of the different forms of negation: negation of the subject (SV), negation of the predicate (PV) and negation of the object (OV) was investigated. It was found that the forms of negation SV, PV and OV were differently recalled and that the two variables semantic implication and animateness of the subject showed a different effect on the recall of these three forms of negation.

     

On the relation of adaptation to field displacement during head movements to the constancy of visual direction

When the normal constancy process on which the apparent immobility of the visualfield during head movements is based was strengthened by the same method that produces adaptation to abnormal conditions in the constancy of visual direction, and when this training of the normal constancy process immediately preceded experimental adaptation, the effectiveness of the latter was diminished. This result applied not only to adaptation to horizontal field displacement and to vertical field displacement during turning of the head, but also to vertical field displacement during nodding of the head, a condition to which adaptation was here demonstrated for the first time.     

Evaluating interobserver reliability of interval data

Previous recommendations to employ occurrence, nonoccurrence, and overall estimates of interobserver reliability for interval data are reviewed. A rationale for comparing obtained reliability to reliability that would result from a random-chance model is explained. Formulae and graphic functions are presented to allow for the determination of chance agreement for each of the three indices, given any obtained per cent of intervals in which a response is recorded to occur. All indices are interpretable throughout the range of possible obtained values for the per cent of intervals in which a response is recorded. The level of chance agreement simply changes with changing values. Statistical procedures that could be used to determine whether obtained reliability is significantly superior to chance reliability are reviewed. These procedures are rejected because they yield significance levels that are partly a function of sample sizes and because there are no general rules to govern acceptable significance levels depending on the sizes of samples employed.