Influential companions: Effects of one strategy on another in the within-subjects designs of cognitive psychology.

Abstract

Within-subjects designs have obvious advantages, but they allow asymmetric transfer from influential companion conditions to bias the results. Examples are given both where asymmetric transfer occurs and where asymmetric transfer probably occurs but is not mentioned. The object of experimenting in the laboratory is to get away from variables that bias the results in unknown ways. Using a within-subjects design puts back the variables, all neatly balanced for subjects and order, but it still biases the results in unknown ways as a result of asymmetric transfer. The asymmetric transfer is attributed to a strategy that is learned in one condition and used in a subsequent condition where it is not . appropriate. Asymmetric transfer probably has its greatest influence when two or more conditions normally require different strategies, when the strategies are unobtrusive, and when the conditions are interleaved randomly within a block of trials.Experimental results have two kinds of explanation. Experimenters like to interpret their results in terms of a theory that is too general to consider all the experimental details. Yet the results may be specific to experimental details that are not incorporated in the theory. The experimental details may either be part of a particular condition or be other conditions included in a within-subjects design when one is used. If so, it may not be valid to generalize the results to performance with different details.An example of a result produced by an experimental detail within a particular condition comes from Broadbent's (1954) early work on noise. An effect of noise that is attributed to distraction can be accounted for simply by the masking of the acoustic cues from the response equipment (Poulton, 1980).The present review is concerned with the second kind of experimental details, the I am grateful to B. B. Murdock for kindly comparing between-and within-subjects designs, to U. Neisser, J. B. Barclay, and D. A. Allport for answering questions about their experiments, and to the British Medical Research Council for financial support.Requests for reprints should be sent to E.

Chewing gum moderates multi-task induced shifts in stress, mood, and alertness. A re-examination

“…Order of condition, however, was not found to interact with gum condition for either stress measure. This suggests that novelty-induced asymmetric transfer (Poulton, 1982) did not occur. Notwithstanding this analysis, sessions were longer in the Scholey et al study indicating that the effects of gum on stress may be limited to more prolonged instances of stress (e.g.…”

The preparation effect in task switching: Carryover of SOA

“…In most cases, the manipulationwas within subjects (blocked or randomized) and did in fact produce switch preparation. The preference for within-subjects designs is unsurprising, given their improved statistical power; nonetheless, such designs leave open the possibility that exposure to different levels of the independent variable produce carryover effects that confound interpretation of the results (Poulton, 1982). In the case of switch preparation, it is at least conceivable that, exposed to random or perhaps even blocked levels of SOA, the system will adopt compromise settings of the parameters that govern preparatory processing in such a way that the anticipated effects of the manipulation are not realized.…”

Failure to maintain equivalence of groups in cognitive research: Evidence from dual-task methodology

“…The following experiment tested the claims made by Poulton (1982) and directly assessed the impact that differential transfer effects may have in research employing within-subject designs such as that reported in Kellas, Simpson, and Ferraro (1988). A portion of the present research replicated the effects found in Kellas, Simpson, and Ferraro, but manipulated task condition within subjects and varied the order in which the three tasks were performed.…”