A test of the effectiveness of the differential-reinforcement-of-low-rate schedule

Pigeons and rats were used in a yoked-control design that equated the reinforcement distributions of differential-reinforcement-of-low-rate and variable-interval schedules. Both a between-subjects design and a within-subjects design found response rate higher for the variable-interval schedule than for the differential-reinforcement-of-low-rate schedule, thus demonstrating the effectiveness of the differential-reinforcement-of-low-rate contingency. The interresponse-time distributions were unimodal for all subjects under the variable-interval schedule and bimodal for pigeons under the differential-reinforcement-of-low-rate schedule. The interresponse-time distributions for rats under the differential-reinforcement-of-low-rate schedule were also bimodal in three of four cases but the height of the modes at the shorter interresponse times were small in both absolute value and in relation to the height of the modes at the shorter interresponse times of the pigeons' distributions.     

The dimensions of career and work orientation in college women

The purpose of this study was to clarify the meaning of the construct, career orientation. Fourteen presumed measures of career orientation as well as Super's Work Values Inventory were administered to college women. Analysis of the relationships among these variables identified two relatively independent clusters. The first cluster most closely approximated the usual definition of career orientation. Career-oriented women were found to be highly career motivated and perceived the career role as primary in their adult lives. The second cluster was called work orientation. This orientation characterized women with well-defined occupational aspirations who placed a high value on both the career role and marriage-family responsibilities in their future. Work-oriented women tended to choose traditionally feminine occupations in contrast to the career-oriented women whose aspirations included higher level and less traditional occupations.     

The focusing of responsibility: An alternative hypothesis in help-demanding situations

The ‘diffusion of responsibility’ hypothesis as an explanation of helping behavior (or lack of same) is qualified by suggesting that the hypothesis applies only in non-interacting situations. It is hypothesized that interacting groups who are aware of a help-demanding situation actually focus the responsibility and, therefore, take action as a group more rapidly than will a non-interacting group. Evidence is gathered in a contrived help-demanding situation employing a 2 × 3 (sex × condition) in which three conditions — alone, non-interacting (pseudo) groups, and interacting groups — are used. The evidence substantiates the major hypothesis. Speculation is also presented concerning the relationship of the ‘alone’ condition to the interacting and non-interacting groups and concerning sex effects.     

Verbal learning: Incremental vs. all-or-none theory

The incremental and all-or-none theories of verbal learning are compared by means of a little-used but methodologically superior variation of the “drop-out” paradigm with paired associates. Earlier experiments purporting to be relevant to the controversy are rejected as failing to offer a conclusive distinction between the two theories. The results presented here are taken to support the incremental theory. It is suggested that irregularities in the results of this and other experiments are caused by several intrusive factors, and a “dual-factor” hypothesis which was put forward to account for these irregularities is questioned on logical and methodological grounds.     

Hemispheric differences in picture-word interference

In a picture-word version of the Stroop task, 30 right-handed subjects were tested under each of six conditions in which a picture alone or a picture plus a word were presented to the left, the right, or both hemispheres. In two additional conditions the picture was presented to the right hemisphere and the word was simultaneously presented to the left hemisphere, or vice versa. For all conditions, subjects were instructed to name the picture only, as rapidly as possible. Picture naming times were significantly slower for the conditions in which the pictures were accompanied by words than in the respective picture alone conditions. Moreover, simultaneous presentation of a picture and a word to both hemispheres resulted in greater interference (slower picture naming times) than did the simultaneous presentation of the picture and the word to either the left hemisphere alone or the right hemisphere alone. The latter two conditions, in turn, resulted in significantly more interference than did the simultaneous presentation of the picture to one hemisphere and the word to the other hemisphere. This pattern of results suggests that the Stroop effect obtained under normal circumstances is in large part a function of the interference caused by the simultaneous processing of items in the same hemisphere. In contrast to hemispheric differences reported for the color-word Stroop task, the effect of presenting a picture and word simultaneously to the right hemisphere did not differ reliably from that of presenting a picture and word to the left hemisphere. The failure to replicate this aspect of the color-word Stroop is attributed to differences in the abilities of the two hemispheres to process the respective target items (the color or the picture) of the two tasks.     

Tactile discrimination of competing sounds

Discriminably different sounds, concurrently presented from the left and right of the medial plane, were reduced in angular separation until subjects could no longer detect which sound was “left” and which was “right.” The procedure was repeated with hearing masked and judgments made on the basis of the tactile signals at two fingertip vibrators that received their inputs from two miniature microphones bilaterally located on the subject’s head. Auditory and tactile performance were compared under active (head movements permitted) and passive (head held still) conditions. Active and passive performance were not significantly different. Auditory and tactile performance became no better than chance at angular separations of 2.7° and 4.4°, respectively. Touch compared sufficiently well with audition to support arguments for the inclusion of sound localization information in devices which use the skin as a substitute for the ear. nt]mis|This research was conducted at the Smith-Kettlewell Institute of Visual Sciences, San Francisco, California. This institute provided the apparatus for the experiment. B. L. Richardson was on Staff Development Leave from the Applied Psychology Department of the Caulfield Institute of Technology, Melbourne, Australia.     

Stimulus stringing by pigeons

Pigeons were trained to peck one, two, three, and then four colors in a predetermined sequence from a five-key array where, over trials, each color appeared equally often in each position of the array. Incorrect pecks resulted in a buzzer and trial termination, with the same array presented for the next trial. Correct pecks produced feedback and correct strings could produce food. All subjects performed at a high level of accuracy with no difference at asymptote between a continuous and a mixed spectral sequence as the required order. Transfer to a new set of arrays had little effect on accuracy. Errors forward in the sequence had the highest probability, followed by repeat errors, backward errors, and dark-key errors. Some arrays had a higher level of accuracy than others but a corresponding systematic variable could not be identified.