SKED-controlled experimentation in an undergraduate instructional laboratory

A SKED-based facility for undergraduate instructional research has been operating for over a year. The two-computer approach, with one machine for programming and the other for running experiments, is used. Criteria for computerized undergraduate research laboratories, benefits of SKED, and the two-computer approach are discussed.     

An observation on set and visual comparison processes

Tasks involving the comparison of sequentially presented stimulus items to determine identity have generally only required interpretation in terms of simple matching. Some studies have attempted to show effects of selective set in these tasks but with little success except in tasks involving comparison of sentences with pictures. By simplifying the task a reliable set effect is demonstrated, showing that a mismatch of certain stimulus attributes only has an identifiable effect on a subject's reaction-time if he may reasonably be supposed to know that the attribute is critical and is set to examine stimulus items for the attribute. Such conditions result in a relatively fast judgement. The finding suggests that the sequential “same“/“different” judgement is a richer source of data concerning recognition and comparison than has been supposed.     

A low-cost interactive coordinate plotter

An inexpensive system for on-line coordinate plotting is described. Users with access to a computer running ALGOL or FORTRAN, and equipped with analog-to-digital converters, can build the system for less than $50. The program is readily modified for the individual user’s requirements, and interactive features allow data correction and analysis to be carried out during coordinate plotting, with operators warned of plotting errors as they occur.     

The effect of aversive consequences upon persistent behavior

It was hypothesized that if a behavior is freely engaged in with the expectancy that an aversive consequence will follow, the intrinsic motivation to perform that behavior will increase when the aversive consequence is no longer present. Subjects either worked on a list of anagrams while receiving electric shock on a VR schedule, while being threatened by electric shock, or in the absence of shock. The experimenter then left the subject alone for 10 minutes with a new list of anagrams. Subjects in the shock condition solved more anagrams on the posttest than subjects in the threat-of-shock and noshock conditions. Subjects in both the shock condition and the threat-of-shock condition reported that they spent more of their free time on the anagrams than subjects in the no-shock condition.     

Pictorial interference with geometric shapes and achromatic shades

In two experiments, subjects were required to match printed names with subsequently displayed achromatic shades or geoinetric shapes. The presence of incongruent shades or shapes at the time of word display substantially slowed the RT for performing the match. This pictorial interference (interference due to a visual, nonlingalistic attributel was substantially attenuated, however, as the delay between the word display and shapes or shades to be matched was increased beyond 100 msec. These findings illnstrate the occurrence of a transitory automatic pathway activation from an irrelevant pictorial attribute, which may be contrasted with the verbal interference effects typically observed in Stroop-naming tasks. In both our tasks and the Stroop task, selectiwe attention fails when a stimulus must be transformed to another form of encoding in the presence of a competing stimulns which is already close to that form.     

A quantitative approach to the study of visual symmetry

An experiment was conducted to explore the quantitative relationship between "goodness" and the amount of symmetry in visual designs. Subjects arranged items in one, two, and three dimensions in an aesthetically pleasing manner. Each design was analyzed to determine its amount of symmetry, and the percent of subjects who created designs having each possible degree of asymmetry was calculated. Perfect symmetry was the most common condition for all three dimensions. Moreover, the goodness of patterns was inversely related to the quantitative degree of asymmetry.     

Vowel recognition: Inferences from studies of forward and backward masking

The recognition of brief vowels was studied in forward and backward masking tasks. In a series of experiments in which both target and mask parameters were systematically varied, two populations of subjects were identified. The majority (Nonmaskers) evidenced little masking at any interstimulus interval, while relatively fewer subjects (Maskers) evidenced backward masking (but not forward masking) over a 100-200 ms interval. Increasing target set size systematically increased masking for the Maskers but not for the Nonmaskers. Adding white noise to the targets increased the extent of masking for both groups. These results suggest (1) that masking does not impose a substantive constraint on vowel perception in running speech, and (2) that multiple strategies may exist for vowel recognition.