Abstract: A Multi-Level Model of Individual Differences in Speed/Accuracy Tradeoff (SATin)

Abstract

Individuals performing an experimental cognitive task have a choice whether to favor accuracy, speed, or weight them both equally. Models of speed/ accuracy tradeoff have been proposed in the assessment literature (van der Linden, 2007) and experimental literature (Ratcliff & Rouder, 1998). However, these models do not estimate individual differences in choice of speed/ accuracy tradeoff at between- and within-subjects levels.

The top of Figure 1 presents the equations and path diagram for the SATin model. Individual differences in speed/ accuracy tradeoff will be modeled at two levels with, 1) variability in Tradeoff (between-subject level, Level 2) and 2) variability in c (within-subject level, Level 1). An individual's Tradeoff factor score represents the individual's distributional position relative to others regarding whether they favor speed (values < 0), accuracy (values > 0), or neither (value = 0). A negative c indicates that the individual is trading off speed and accuracy for these particular trials, whereas a positive and zero c indicate the individual is not trading off.

FIGURE 1 SATin Model Diagram.

Panels 1 and 2 illustrate Simpson's paradox, where speed/ accuracy tradeoff occurs in opposing directions at between- and within-subject levels. This highlights the need for a multi-level model as the researcher would draw opposing conclusions by observing only one of these levels. Simulations studies compared the SATin model to a popular model in cognitive psychology that uses speed alone to estimate ability. SATin outperformed this model by accounting for substantially more variance in actual ability.

Acknowledgments

Dan Johnson would like to express his appreciation for SMEP member, Dr. Joseph Rodgers, for sponsoring this project.

Acknowledgments

Dan Johnson would like to express his appreciation for SMEP member, Dr. Joseph Rodgers, for sponsoring this project.