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The 5s were shown a series of six to-be-remembered items (positive set) composed of two subsets (letters and digits) followed by a test or probe stimulus. If the probe was a. member of the series, 5s were instructed to say "yes," and "no" if otherwise. Reaction time (RT) increased with increases in the size of the probed subsets. When positive sets were followed by an informative (I) cue, 5s utilized a directed search strategy and confined their search to only the probed subset. When cues were noninformative (T), a majority of 5s used a nondirected search which elevated RT and decreased the slope of the function relating RT to size of the probed subset. Grouping of subsets in the positive set facilitated RT only when accompanied by informative retrieval cues.

A reaction time (RT) experiment was conducted to examine the influence, on retrieval time, of temporal organization of subspan sets of digits. The 5s were shown five, six, or seven to-be-remembered digits followed by a probe stimulus to which they were to give the name of the item that had followed the probe in the series. Brief temporal pauses interpolated near the middle of the six-and seven-digit strings produced marked changes in the serial position curves. The results were discussed in terms of a directed memory search which was influenced by the organization of information in memory.

A recognition mernory experiment investigated Ss' ability to organize information in short-term memory, A paradigm similar to that used by Sternberg was employed. A sequentially presented series of six digits (positive set) was shown with each digit appearing on a red, green, or amber background. The colors defined different ensembles, and responding to a test digit was contingent upon an item's membership in the positive set and the color-defined ensemble. Reaction time (RT) to the test digits indicated that Ss did organize information into ensembles. Furthermore, when informative cues were presented prior to the test item, Ss direeted and confined their seareh to the eued subset. Sternberg (1966) introduced a method for investigating the search strategies used by Ss in a recognition memory task. Ss were shown a sequentially presented set of homogeneous stimuli (digits), called the positive set, and then shown a test or probe stimulus to which they were instructed to make a first response (positive) if the probe stimulus was identical to any member of the positive set and a second response (negative) otherwise. It was found that reaction time (RT) increased linearly as a function of the size of the positive set for both positive and negative responses, with the slopes of both functions being equal. These findings led Sternberg to propose a theory of high-speed scanning in which an internal representation of the test item is compared successively to the items in memory at an average rate of approximately 25 to 30 items per second. A positive response is made if there has been a match, and a negative response is made otherwise. Since RT increased with positive set size at the same rate for positive and negative responses, the search was postulated to be exhaustive rather than self-terminating. If the search were terminated when a match was made, the positive probes should have resulted, on the average, in half as many eomparisons as the negative probes, reducing the slope by one-half. Sternberg (1969) reported equivalent results for both long-term memory (LTM) and short-term memory (STM), and hypothesized that "the same memory system was being scanned: that s, when information in inactive memory ... [LTM] has to be used, it may be entered also in active memory ... md thus becomes more readily available [po 430] ."Recently, variations of Sternberg's paradigm have reen used to study the organization of information in ;TM and LTM. In an LTM study, Forrin and Morin ) 967) demonstrated that stimuli in sets composed of *This investigation was supported bv National Scienee "oundation Grant GB-16729 awarded to Bowling Green State Jniversity and the seeond author.[Requests for reprints should be sent to Donald V. DeRosa, Jepartment of Psychology, Bowling Green State University, Jowling Green, Ohio 43403. letters and digits could be named faster if Ss were informed of an item's set (number or symbol) membership prior to presentation. Briggs and Swanson (1969) also employed a naming task using sets of random figures with 2...