Rehearsal strategies and the serial-position curve in immediate free recall of ordered items

Immediate free recall of random strings of 10 numbers was studied under four experimental conditions: as each number was presented, subjects either had to recall the previous number (Recall n-1), recall the number just presented (Recall n), read the number (Read aloud), or were silent (Free Recall). Overall recall was the same in all conditions. Recall and order of recall by serial-position changed systematically, with an increasing recency and decreasing primacy effect from Free Recall through Read Aloud and Recall n to Recall n-1. These changes in recall order and serial-position curves suggest that differential rehearsal of items is decreased by requiring retrieval during presentation.     

A response time model for choice behavior

A subject in a two-choice situation characteristically makes several observing responses before performing the final choice. This behavior can be described by means of a random walk model. The present paper explores some possibilities as to how this model can be extended to include choice time. The assumption is made that the duration of each step in the random walk is a random variable which is exponentially distributed. With this assumption, one can predict the probability distributions of the choice times as well as the moments of these distributions.The author gratefully acknowledges his debt to W. K. Estes and C. J. Burke. This study was initiated while the author held a USPHS postdoctoral fellowship at Indiana University.     

Delayed reinforcement and runway performance

The Psychological Record -     

Frequency distribution of interresponse times during VI and VR reinforcement

A detailed analysis was made of the interresponse times (IRTs) of two rats under both a VI 40-sec and a VR 15-sec schedule. Except for the latency of the first response after a reinforcement, the mean IRTs of all further responses differed little. Similarly, the frequency distributions of the successive IRTs did not vary greatly, but were of no simple form. Sequential dependencies between successive IRTs were small, never accounting for more than 1% of the variance.     

How does background information improve memory for text content?

In two experiments, we investigated whether reading background information benefits memory for text content by influencing the amount of content encoded or the organization of the encoded content. In Experiment 1, half of the participants read background information about the issues to be discussed in the text material, whereas half did not. All the participants were then tested for free recall and cued recall of text content. Free recall was greater for individuals who read issue information than for those who did not. The groups did not differ on cued recall, suggesting that background information did not facilitate the encoding of more text content. Measures of representational organization indicated that increased recall in the issue information group resulted from better organization of content in memory. Experiment 2 extended these findings, using background information about text sources, demonstrated that the efficacy of background information depends on the semantic relationship between that information and text content.     

The role of imagery in the evaluation of sentences

Reaction time was the dependent variable in this sentence verification experiment. Simple sentences, which were either true or false, were constructed such that in some cases it was easy to form an image of the sentence, and in other cases forming an image was difficult. Ss' ratings were employed to select low- and high-imagery sentences. It was found that high-imagery sentences could be verified more rapidly than low-imagery sentences. Instructions which did not mention imagery were given to some Ss while others were specifically asked to employ imagery, but the reaction times of these two groups of Ss did not differ. It was concluded that imagery facilitates the process of sentence verification and that models of this process which restrict themselves to purely semantic operations are incomplete.     

Prompt comprehension in UNIX command production

We hypothesize that a cognitive analysis based on the construction-integration theory of comprehension (Kintsch, 1988) can predict what is difficult about generating complex composite commands in the UNIX operating system. We provide empirical support for assumptions of the Doane, Kintsch, and Polson (1989, 1990) construction-integration model for generating complex commands in UNIX. We asked users whose UNIX experience varied to produce complex UNIX commands, and then provided help prompts whenever the commands that they produced were erroneous. The help prompts were designed to assist subjects with respect to both the knowledge and the memory processes that our UNIX modeling efforts have suggested are lacking in less expert users. It appears that experts respond to different prompts than do novices. Expert performance is helped by the presentation of abstract information, whereas novice and intermediate performance is modified by presentation of concrete information. Second, while presentation of specific prompts helps less expert subjects, they do not provide sufficient information to obtain correct performance. Our analyses suggest that information about the ordering of commands is required to help the less expert with both knowledge and memory load problems in a manner consistent with skill acquisition theories.