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Free recall is a basic paradigm of experimental psychology. In this paradigm, participants study a list of items on each trial, and then are prompted to recall the items in any order (hence the name "free" recall). Items are usually presented one at a time for a short duration, and can be any of a number of nameable materials, though traditionally words, randomly chosen from a larger set, are used. The recall period traditionally lasts a few minutes, and can involve spoken recall or written recall. The standard paradigm involves the recall period starting immediately after the final list item; this can be referred to as Immediate Free Recall (IFR) to distinguish it from Delayed Free Recall (DFR), in which a short distraction period is interpolated between the final list item, and the start of the recall period.
One of the basic measures of performance in the free recall paradigm is simply the number of words recalled from a list, which varies with a number of factors, including the list length, the type of material studied, and any task used to process the words (e.g., a simple judgement). When one examines the probability of recall by the position of the item in the list (its serial position), one finds that the initial and terminal items in the list are better remembered than those in the middle (also known as the primacy and recency items, respectively). Murdock (1962) presents a classic study of serial position effects in free recall. One also finds evidence of the recency effect in the way that participants initiate recall of a list: they most often start with terminal (recent) list items (an early description of the recency effect in the probability of first recall can be found in Hogan, 1975).
Beyond examining the relative probability of particular items being recalled, one can examine the order in which items are retrieved during the recall period. When a participant is asked to recall a set of random words, there is a marked tendency for items from neighboring positions in the study set to also be recalled successively (also known as the contiguity effect, and characterized by Kahana, 1996).
Classic studies of free recall often focused on the multi-trial free recall paradigm, in which the same set of items appear on successive trials (although usually the order of the items is scrambled across trials). In this version of the paradigm, researchers would focus on how many trials it took to learn a certain proportion of the items. Tulving (1968) describes the phenomenon of subjective organization, in which words that are recalled successively during the first recall period also tend to be recalled successively during later recall periods.
- Murdock, Bennet B (1962). The serial position effect of free recall. Psychological Review 64 (5): 482–488.
- Hogan, R. M. (1975). Interitem encoding and directed search in free recall. Memory and Cognition 3 (2): 197–209.
- Kahana, Michael J (1996). Associative retrieval processes in free recall.. Memory and Cognition 24: 103–109.
- Tulving, Endel (1968). "Theoretical issues in free recall" Verbal Behavior and General Behavior Theory, Chapter 1, 2–36, Prentice-Hall.