Dynamic visuometric techniques

A general technique is described to automate the measurement of visual thresholds. The method is based on the dynamic analog of the method of adjustment, incorporating continuous feedback. Threshold is treated as a system interaction between some level of response and sensed input. The S tracks a stimulus that continually oscillates in magnitude around threshold. The accuracy and variability of the S’s response provides a dynamic and functional assessment of the threshold under the condition of the experiment. Techniques for instrumenting several visuometric procedures are described.     

Tables of event sequences for sequential analyses of data in psychological experiments containing two-class events

Tables of sequences of two-class events are presented for use in programming psychological experiments in which behavior on trial n may be a function of the events of trials n ? 1, n ? 2, and/or n ? 3. Various factors related to schedule generation are discussed, i.e., restrictions on trial-block length which accompany sequential balance, interrelationships of trial blocks in the multiblock experiment, relationships between run length and r-tuple occurrences, and alternation behavior. Following a consideration of various methods of schedule generation for the two-class experiment, it was concluded that no method can result in schedules that possess all properties considered desirable in psychological experiments. However, the present sequences allow for sequential balance and analysis, and thus should prove useful in producing schedules in some contexts that are standard with regard to sequential influences.     

Do depth shifts resulting from an interocular delay in stimulation result from a breakdown of binocular fusion?

Previous studies have shown that the introduction of an interocular delay in presentation to the two eyes of a briefly viewed, haploscopically presented object resulted in a rearward shift in the depth position of this object. The present study investigated the magnitude of this depth shift as a function of flash duration and determined the relationship of this magnitude to two-flash and simultaneity thresholds. It was found that depth shift magnitude decreased as flash duration increased, and that large depth shifts were associated with large two-flash thresholds. The hypothesis that depth shifts can occur within the temporal limits of binocular fusion was supported.     

Subjective uncertainty,the orientation reaction,and the reinforcement of an instrumental response

In Experiment 1, Ss were exposed to slides of intermediate blur for 5, 10, 30, or 60 sec and were asked to guess the identity of the blurred object and to estimate how confident they were of each guess. The S’s task in Experiment 2 was merely to view the blurred slides while S’s EEG waves were being recorded. After being exposed to a blurred slide for a certain duration, in Experiment 3, Ss were required, by means of a key press, to choose to view either a clear version of the blurred slide or an unrelated clear picture. Uncertainty/second, EEG desynchronization/’second, and related choices were all found to be a negatively sloped function of viewing duration.     

Violations of visual simultaneity

We present the result of two experiments that demonstrate an ability on the part of Os to detect asynchronies in visual stimuli with in the range of 0-100 msec. Such results are additional examples of an ability on the part of the human O to use information about temporal order to a precision beyond the usual results of visual “simultaneity” experiments. Thus the conventional nations of simultaneity and its corollary, the psychological moment, may be reflections of psychophysical technique rather than the biological function of sensory systems.     

Redistributing control between the elements of a compound stimulus

Twenty-eight pigeons were given discrimination training. Four groups were run in which for 0, 2, 4 and 9 sessions of training colour was an irrelevant cue and tone was relevant. Generalization tests were given in extinction; the training colour (C₁) and another colour (C₂) were presented with tone (T) and noise (N). Responding to these four stimulus combinations, TC₁, TC₂, NC₁ and NC₂, allowed the assessment of control by colour and tone. A reduction of control by colour and an increase in control by tone were found to be positively related to the amount of training with colour irrelevant. Tests showed a strong inverse relationship between control by colour and tone.     

The symmetrical maze: An automated closed-field test series for rats

An automated “intelligence” test for rats is described. Supporting data indicate that this maze-problem series is sensitive to hypothyroidism-induced learning deficit and sex differences. Comparisons between this new problem set and the Rabinovitch-Rosvold (1951) closed-field tests are presented with respect to difficulty, internal consistency, and test-retest reliability.