Two-component theory of the suffix effect: Contrary findings.

Abstract

The suffix effect is the reduction in the recallability of the last few items of a just-spoken list caused by appending a nominally irrelevant item, or suffix. The effect is widely assumed to comprise a "structural" terminal component, affecting just the last item, and a strategy-sensitive preterminal component. In a series of 8 experiments, the authors fail to replicate any of a variety of findings widely cited as the empirical basis for this 2-component theory. The authors also question the support that earlier findings provide for the theory, even if they had proved replicable. They attribute the entire suffix effect to the grouping of the suffix with the list items.

Exploring the suffix effect in serial visuospatial short-term memory

“…Although the suffix effect has been examined repeatedly in the verbal literature (e.g., Bloom & Watkins, 1999;Crowder & Morton, 1969;Penney, 1985;Watkins & Watkins, 1980), aside from the present study we are not aware of any investigation directly examining the suffix effect in visuospatial serial memory. The suffix effect found in our experiments adds to the increasing evidence pointing out the functional similarities of verbal and nonverbal memory (Avons, 1998;Avons & Masson, 1999;Farrand & Jones, 1996;Jones et al, 1995), insofar as recency for visuospatial items was affected by a suffix of the same modality.…”

Two-component theory of the suffix effect: Contrary evidence

“…There are, however, serious empirical challenges to the theory. Aside from a failure to replicate many of the findings on which the theory is grounded (Bloom & Watkins, 1999), there is evidence contrary to the theory's core assumption that the terminal component of the suffix effect is immune to topdown, conceptual influence. An ambiguous suffix (wah) has a much stronger detrimental effect on recall of a final verbal list item if the suffix is framed as a verbal utterance, rather than as a nonverbal sound, such as a muted trumpet note (Ayres, Jonides, Reitman, Egan, & Howard, 1979).…”

“…Following Penney (1985) and Bloom and Watkins (1999), statistical analyses for all eight experiments in the present report focused on the final four positions, of which the three prior to the last were referred to as preterminal positions (or collectively, as the preterminal position) and the last as the terminal position. All t tests were two-tailed.…”

“…Indeed, of the 34 references to the theory turned up in a review of the literature, 1 only 1 (Bloom & Watkins, 1999) expressed dissent. There are, however, serious empirical challenges to the theory.…”

“…And Experiment 8 shows that the conventional effect of separating the suffix from the list items also occurs with a static, visual mode of presentation. It is suggested that these findings, and the suffix effect literature in general, can be usefully interpreted in terms of perceptual grouping (see Bloom & Watkins, 1999;see also de Gelder & Vroomen, 1992;Kahneman, 1973;, including the principles of similarity (e.g., Darwin & Baddeley, 1974) and proximity (e.g., Frankish & Turner, 1984).…”