Robert Karsh’s research while affiliated with U.S. Army Engineer Research and Development Center and other places

Permitting subjects to choose materials to be learned on a task enhances performance on that task. These results support the idea that choice increases the learner's perception of control, thereby enhancing motivation and performance. The purpose of the present experiments was to determine whether choosing responses to be learned on a paired-associate task would also benefit performance on a reaction-time task. Half of the subjects selected their responses to be learned on a paired-associate task while the remaining subjects were assigned responses. In one experiment, subjects then performed both the PA and RT tasks simultaneously, while in the second experiment the RT task was performed following the choice/force procedure. Providing the learner with the opportunity to choose produced a generalized increase in motivation, which resulted in significantly faster responding on the nonchosen RT task. Also discussed are the limitations of the effects of perceived control.

There has been an increasing emphasis in psychology on the perception of control over one''s environment and its effect on behavior and performance. In the present experiment, subjects were allowed to choose material they would like to learn if given the opportunity, or allowed to choose material for others to learn. Their learning of a nonchosen (forced) set of materials was then examined and compared with that of subjects given no opportunity to choose at all. It was found that the choice-for-self condition led to better performance than either the choice-for-other condition or the nochoice (forced) condition. However, when an additional group of subjects was given the opportunity to choose for others and their personal involvement was augmented by emphasizing their willingness to choose, their performance was enhanced relative to subjects offered no choice. The results were discussed in terms of motivational benefits stemming from perceived control.

An experiment was conducted to determine the effect of manipulating S's preparation for what he will see on a given trial on his ability to mentally keep track of the number of occurrences of each of several different stimuli in a sequence. It was found that, when the same stimuli were used from trial to trial, performance was significantly better than when different stimuli were used. Foreknowledge of the specific stimuli to be used on a given trial did little to improve performance per se, but it did reduce labeling errors. The results were discussed in terms of the "spatial window" model of keeping-track performance.

Conducted an experiment with 132 college students to compare the disruptive effects of irrelevant information (names of colors) superimposed on relevant information (bands of colors) with the effects of irrelevant information occupying the interval between stimuli. Irrelevant information disrupted performance only when it occupied the interval between stimuli, suggesting that interference was primarily with the rehearsal process and not with the perceptual process. It made no difference whether the names of colors were the same as or different from the bands of colors. Analysis of control conditions suggests that Ss can better "keep track" of colors than color names. Results are discussed in terms of visual imagery and the spatial window model of "keeping-track" performance. (French summary) (16 ref.)

Required 154 undergraduates to keep track mentally of the number of occurrences of each of 4 different symbols presented sequentially. It was found that when irrelevant information which closely resembled relevant information was introduced into the sequence performance was disrupted. Delaying identification of relevancy further disrupted performance. The disruption was not attributable to the resulting irregularity of presentation. The detrimental effects of irregular presentation rates were eliminated by insertion of cues enabling Ss to pace rehearsals of their mental tallies. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

The ability to keep track of sequential events was examined as a function of on-off ratio and the number of items simultaneously displayed. On-off ratio did not affect performance while the number of items simultaneously displayed did. Implications for a theory of keeping-track performance are discussed.

Notes that previous studies have not been effective in minimizing the temporal dependencies which have favored auditory over visual performance in short-term memory. 2 experiments were conducted using the keeping-track task which has been shown to place importance upon spatial relationships during encoding and storage. Exp. I, with 18 undergraduates, resulted in fewer errors being made during the auditory presentations, suggesting the possibility of differences in the encoding task for each mode. Exp. 2, with 18 undergraduates, attempted to equate the encoding tasks and resulted in the same level of performance for each mode. Results are interpreted as giving support to the "spatial window" model. Both modes were found to be capable of spatial encoding and storage. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Examined the ability to keep track of sequential events as a function of the rate of stimulus presentation and the number of categories of information displayed simultaneously. Results from 90 undergraduates show that performance was a function of the "information rate" defined as the 1st aforementioned variable divided by the 2nd variable. Implications for a theory of keeping-track performance are discussed. (PsycINFO Database Record (c) 2012 APA, all rights reserved)

Applied the "spatial window" model of encoding to keeping-track performance with auditory stimuli. Results indicate that spatial encoding can play a role in short-term memory irrespective of the stimulus modality employed. Further, a complex relation was found between encoding time, rehearsal time, and the nature of the stimulus materials. (PsycINFO Database Record (c) 2012 APA, all rights reserved)