Modification of a response bias through differential amount of reinforcement

A procedure is described for assessing response bias to either the form or color dimension of a compound standard stimulus. Responding was assessed under conditions of equal reinforcement (three tokens) for responding to either the form or color dimension. Under these conditions, the four male subjects (aged 7 to 11 yr) differentially responded to the form dimension. After a bias was assessed, the number of tokens delivered contingent upon form responses was reduced. After a reversal in differential responding, the equal-reinforcement condition was reintroduced. Two of the subjects returned to their initial response bias when equal reinforcement for either dimensional response was reintroduced, and two maintained the reversal established during the differential-reinforcement phase. For the latter two subjects, differential reinforcement was again imposed, in favor of form. This partial replication reinstated their original pattern of response bias.     

Testing independence in two-way contingency tables with data subject to misclassification

The misclassification process is represented by a stochastic matrix containing the probabilities that an individual who belongs in one cell is counted as belonging to another (or perhaps the same) cell. These probabilities are supposed known. If misclassification in the row direction is independent of that along the column variable then the size of the usual chi-square test is unchanged. It is shown how to calculate loss of power in this case and also how to calculate the change in size of the test if the errors are not independent. A modified test criterion is suggested when errors are not independent and a numerical example is included.     

Student Opinion on the Location of Occupational Information on a University Campus

A questionnaire survey revealed student needs, knowledge, and use of occupational information, as well as opinions about the most suitable location of such a resource on the Oregon State University campus. Results indicated that most students did not know where occupational information was available and only a small percentage knew there were occupational files in the Counseling Center and the University library. The great majority (almost 9 out of 10) wanted the University to provide a central occupational library, with most naming the Student Union (40 per cent) or the University library (25 per cent) as the best location. The Counseling Center was mentioned by only 2 per cent of the students.     

The perception of multiple simultaneously presented forms as a function of foveal spacing

Using five capital letters as the form stimuli and tachistoscopic presentation, an exposure duration was determined for each S that yielded 80% identification accuracy when single letter displays were presented. Then the increment in exposure duration necessary for a correct identification of all letters on a display on 80% of the trials was determined for 2, 3, and 4 letter displays. In view of evidence that perceptual independence breaks down when stimuli are spaced much closer than 1° apart in the fovea, the effect of different foveal spacing of the form stimuli in the display was studied. Spacings of 1/2, 3/4, and 1° of angle were employed. Less than a 30% increment in exposure duration was necessary to recognize 2 form displays at the same accuracy level as single form. But no further increase in exposure duration was necessary to recognize 3 and 4 form displays at the same accuracy criterion. Evidence for positive correlation of sensory perceptual error for forms spaced less than 1° apart in the fovea was found.     

Some observations and measurements of the Panum phenomenon

The angular separation between the “binocular” and the “monocular” line of Panum’s limiting case was systematically varied under conditions in which the changes in seen relative depth could be quantified. Stereoscopic, equidistant, and anomalous depth localizations were seen. A criterion of variability of depth localization was utilized to differentiate the mechanism operative in determining the seen depth. When stereopsis is clearly present, depth in Panum’s limiting case is predictable and reveals a one-to-one relationship with the angle of lateral separation of the stereoscopic stimuli, i.e., the odd line cooperates in free binocular vision with both of the paired lines to give “true” stereoscopic depth. The range of angular separation over which Panum’s limiting case will give rise to stereoscopic depth is increased by free eye movements well beyond the usually reported limits of Panum’s retinal areas.