Task-switching cost and repetition priming: Two overlooked confounds in the fixed-set procedure of the Sternberg paradigm and how they affect memory set-size effects

Abstract

Subjects performed Sternberg-type memory recognition tasks (Sternberg paradigm) in four experiments. Category-instance names were used as learning and testing materials. Sternberg's original experiments demonstrated a linear relation between reaction time (RT) and memory-set size (MSS). A few later studies found no relation, and other studies found a nonlinear relation (logarithmic) between the two variables. These deviations were used as evidence undermining Sternberg's serial scan theory. This study identified two confounding variables in the fixed-set procedure of the paradigm (where multiple probes are presented at test for a learned memory set) that could generate a MSS RT function that was either flat or logarithmic rather than linearly increasing. These two confounding variables were task-switching cost and repetition priming. The former factor worked against smaller memory sets and in favour of larger sets whereas the latter factor worked in the opposite way. Results demonstrated that a null or a logarithmic RT-to-MSS relation could be the artefact of the combined effects of these two variables. The Sternberg paradigm has been used widely in memory research, and a thorough understanding of the subtle methodological pitfalls is crucial. It is suggested that a varied-set procedure (where only one probe is presented at test for a learned memory set) is a more contamination-free procedure for measuring the MSS effects, and that if a fixed-set procedure is used, it is worthwhile examining the RT function of the very first trials across the MSSs, which are presumably relatively free of contamination by the subsequent trials.

In Defence of High-Speed Memory Scanning

“…This finding appears not to have been considered by advocates of strength-based theories of performance in this task (e.g., Dosher, 1989, who believe that recency across trials is one determinant of RT, and Hockley & Murdock, 1987). Nor have these findings been considered by those who argue that repetition priming plays a role in the fixed-set procedure (Jou, 2014;Stadler & Logan, 1989).…”

The Effects of Increasing Semantic-Associate List Length on the Deese–Roediger–McDermott False Recognition Memory: Dual False-Memory Process in Retrieval from Sub- and Supraspan Lists

“…In a typical DRM recognition experiment, MSS and the number of probes at test are not varied; therefore, using a fixed-set testing procedure is not a problem. However, as indicated by Jou (2014), when MSS is varied as in this study, using a fixed-set testing procedure introduces confounds (RTs of shorter lists with fewer probes at test are impacted by the task-switching cost to a greater extent than longer lists). Hence, the single-probe test is the only confound-free way to measure the recognition time with the result of obtaining an overall slower response.…”

“…For this reason, subjects did not have to resort to the recollective retrieval process. A quick, direct familiarity check involving limited search was sufficient for rejecting a negative probe based on a lack of a familiarity feeling (although this process is not as useful for recognizing a positive probe) resulting in faster negative responses than positive responses (Atkinson & Juola, 1973;Banks & Atkinson, 1974;Jou, 2014;Roediger, Knight, & Kantowitz, 1977, also obtained faster negative than positive responses).…”

“…Only one probe was presented for a learned list of words to prevent possible confounding from contextual factors when multiple probes are tested on a list of learned words (Jou, 2014). As Jou (2014) showed, this single probe test procedure will elevate the RT due to a task-switching cost (Mayr & Kliegl, 2000;Monsell, 2003;Monsell, Sumner, & Waters, 2003;Rogers & Monsell, 1995). A control condition using unrelated word lists was employed to serve as a baseline condition to see how the RT functions of the DRM words could differ from that of the semantically unrelated words.…”

“…The presented words were randomly selected from the 15 words in a list for each subject, except for the critical word, which was designated for each list. We adopted Sternberg's varied-set testing procedure in which only one probe was tested for a learned list of words (Sternberg, 1966(Sternberg, , 1969 to avoid potential confounds in a fixed-set procedure in which multiple probes are tested for a learned list of words (see Jou, 2014, for a detailed explanation). 4…”