Two Faces of the Conceptual Peg Hypothesis

The present study investigated why it is that the more concrete the subject noun phrase of a sentence, the more likely the predicate is to be recalled when the subject noun phrase is the cue. The findings were that concretization dramatically influences both the probability of recognition of the subject noun phrase and the probability of recall of the predicate given recognition. These results were taken to mean that a concrete phrase makes a good conceptual peg because it is likely to be given a specific, stable encoding and because it tends to redintegrate the whole sentence. Regression analysis showed that the concreteness effect could not be attributed to an influence on comprehensibility. A model of sentence memory is offered which can account for the results. Conceptual Peg Hypothesis 2 Two Faces of the Conceptual Peg Hypothesis It is well known that concrete language makes word pairs and sentences more memorable. The most widely accepted explanation for this fact is that concrete words readily form integrated, holistic units, often conceived to take the form of mental images (cf. Paivio, 1971). Several lines of evidence support the hypothesis that it is the holistic character of the mental representations to which concrete words and concretizing operations give rise that accounts for their facilitative effect. For example, Begg (1972) compared cued recall and free recall of noun phrases. He found that when both the adjective and noun were concrete, such as in rusty engine, cued recall of either phrase constituent using the other word as the cue was much better than free recall. For phrases composed of abstract adjectives and nouns, such as absolute truth, cued recall was no better than free recall. When subjects do not spontaneously construct unified representations-or conditions are contrived to work against such organization--imagery instructions, pictures, drawings, and concrete words lose their potency. Experiments comparing separate pictures with pictures integrating the stimulus and response elements into a single scene invariably show a distinct advantage for the composite pictures (Epstein, Rock, & Zuckerman, 1960; Davidson, 1964; Reese, 1965). Bower (1972) found that subjects asked to bring to mind a scene of two objects interacting in some way recalled substantially more than subjects told "to imagine the two objects one at a time in their imaginal space, like two pictures being seen on opposite walls of a room." Finally, Rohwer (1967) found that placing a verb or a preposition Conceptual Peg Hypothesis 3 between two concrete nouns (the rock breaks the bottle, the rock behind the bottle) facilitated learning whereas connecting them with a conjunction (the rock and the bottle) did not. In summary, there is a quite convincing case that it is the quality of being easily organized into unified mental representations which accounts for the advantage of concrete elements. A very different interpretation of the concreteness effect can be derived from the encoding variability hypothesis of Martin (1968) and the complementary concept of encoding specificity (cf. Tulving & Thompson, 1973). Martin has developed a two-stage model of cued recall performance. According to this model, when the cue is presented it must make contact with the representation of the cue stored during study. Next the response must be accessed from this stored representation. The first stage will succeed only when the cue is given the same encoding at the test as it was during study. If the two encodings fail to match, recall can not occur. It stands to reason that a concrete, denotatively specific term will permit fewer encodings than an abstract term. Consequently, concreteness could increase the probability that the encodings of the cue at test and study will match rather than the likelihood of an integrated representation. It would appear, then, that there are at least two versions of the "conceptual peg" hypothesis (Paivio, 1969, 1972). The one which Paivio favors is that the concrete cue is more likely to evoke the whole idea, that is, that it has greater "redintegrative power" (Horowitz & Prytulak, 1969). But a plausible alternative is that concrete stimuli are more recognizable than abstract stimuli because there is a higher probability that they will have been given specific, stable encodings. Conceptual Peg Hypothesis 4 To date, the only direct experimental tests of these two explanations for the effects of concreteness have been completed by Wicker and his associates (Wicker, 1970; Wicker & Evertson, 1972), who have investigated picture-word differences using a paired associate task. Drawings or concrete nouns representing the same common objects were, respectively, the concrete and less concrete stimuli; A combined recognition and recall test included new drawings and words to serve as distractors. For each item, the subject indicated whether it was old or new and, if judged old, attempted to give the response element. These experiments have consistently shown better recognition of pictures than words, suggesting less encoding variability of the more concrete stimulus. However, no differences in recall conditional upon recognition have appeared, a fact inconsistent with the redintegration hypothesis. Hence, the results appear to differentially support the encoding specificity interpretation of the concreteness effect. There are at least two reasons for not accepting Wicker's results at face value, however. First, like many other experiments of this general type (cf. Martin, 1967), it can be argued that recognition was confounded with capacity to recall. When a subject judged a cue to be old, he was immediately thereafter expected to produce a response. This task demand may have caused the criterion for saying "old" to shift depending upon whether a response was available. If this happened, of course, the data would give the appearance of locating the concreteness effect in the recognition phase even though it was really due to redintegration. In the experiment reported here, the recognition test preceded and was completely separate from the recall test. While response availability may still have Conceptual Peg Hypothesis 5 affected the old/new judgement, at least gross confounding was avoided; our procedures did not invite a recognition strategy based on whether or not the rest of the configuration could be recalled. There is a second reason for not counting Wicker's data too heavily against the redintegration hypothesis. His pairs were completely arbitrary, and arbitrary concantenations do not necessarily form units (Horowitz & Prytulak, 1969). Redintegration depends upon there being holistic images (Begg, 1972) or, perhaps, unified propositions (Kintsch, 1974) so that there is something to be redintegrated. The present experiment employed meaningful sentence pairs of the kind used by Anderson (1974). One sentence in each pair contained a concretelymodified subject noun phrase, the other a redundantly-modified subject noun phrase. Below are some examples: The traditional customs fascinated the tourists. The tribal marriage customs fascinated the tourists. The parking regulations annoyed the salesman. The official regulations annoyed the salesman. The set of official regulations, for instance, is not much smaller than the set of all regulations, whereas parking regulations are a distinctly smaller subset. In other words, the concrete phrases were more denotatively specific than the redundant ones. Anderson (Experiment II) found that subjects were about one-and-one-half times as likely to recall the predicates of sentences which began with concrete than redundant subject noun phrases, Conceptual Peg Hypothesis 6 given the subject noun phrases as cues. The purpose of the experiment described herein was to determine whether the advantage of the concrete phrases can be attributed to their superior recognizability or their capacity to redintegrate whole ideas.