Disruptive effects of prior information on tachistoscopic recognition

Smith, Haviland, Reder, Brownell, and Adams (1976) found tachistoscopic letter recognition to be disrupted by advance information about possible letter alternatives. An association of “before-disruption” with a bias to respond “same” in same-different judgment led Smith et al. to conclude that incidental mask features corresponding to a precued letter were erroneously incorporated into the target letter decision. Experiments 1 and 2 in the present study failed to replicate the before-disruption effect under conditions similar to those of Smith et al., although precuing produced a strong bias to respond “same.” Similarity between “same” and “different” alternatives was manipulated in Experiment 3 by selecting letter pairs differing in one critical feature (P-R, O-Q, C-G, F-E) for one group of subjects, and re-pairing the same letters (P-G, O-E, C-R, F-Q) for another group. Contrary to Smith et el., precuing interacted significantly with pair similarity, such that before-disruption occurred only with similar alternatives. In contrast, precuing produced equivalent “same-bias” in both groups. The dependence of before-disruption on pair similarity was extended to two-alternative forced-choice recognition in Experiment 4. Together with inconsistencies in the Smith et al. data and more detailed analysis of present recognition errors, the results suggest (1) the before-disruption and same-bias effects of precuing are mediated by separate mechanisms, and (2) before-disruption reflects loss of target letter information rather than direct incorporation of extraneous mask features.