Scoring Alternatives for Mental Speed Tests: Measurement Issues and Validity for Working Memory Capacity and the Attentional Blink Effect

Abstract

Research suggests that the relation of mental speed with working memory capacity (WMC) depends on complexity and scoring methods of speed tasks and the type of task used to assess capacity limits in working memory. In the present study, we included conventional binding/updating measures of WMC as well as rapid serial visual presentation paradigms. The latter allowed for a computation of the attentional blink (AB) effect that was argued to measure capacity limitations at the encoding stage of working memory. Mental speed was assessed with a set of tasks and scored by diverse methods, including response time (RT) based scores, as well as ex-Gaussian and diffusion model parameterization. Relations of latent factors were investigated using structure equation modeling techniques. RT-based scores of mental speed yielded substantial correlations with WMC but only weak relations with the AB effect, while WMC and the AB magnitude were independent. The strength of the speed-WMC relation was shown to depend on task type. Additionally, the increase in predictive validity across RT quantiles changed across task types, suggesting that the worst performance rule (WPR) depends on task characteristics. In contrast to the latter, relations of speed with the AB effect did not change across RT quantiles. Relations of the model parameters were consistently found for the ex-Gaussian tau parameter and the diffusion model drift rate. However, depending on task type, other parameters showed plausible relations as well. The finding that characteristics of mental speed tasks determined the overall strength of relations with WMC, the occurrence of a WPR effect, and the specific pattern of relations of model parameters, implies that mental speed tasks are not exchangeable measurement tools. In spite of reflecting a general factor of mental speed, different speed tasks possess different requirements, supporting the notion of mental speed as a hierarchical construct.

Keywords: attentional blink; mental speed; response time modeling; working memory capacity.

Figure A1

Scatterplots and correlations across participants of model implied and observed RTs for five quantiles (0.10, 0.25, 0.50, 0.75, and 0.90) of the RT distribution.

Figure 1

Diffusion model for binary decision tasks.

Figure 2

(a) Rapid Serial Visual Presentation (RSVP) Paradigm and (b) Attentional Blink (AB) effect.

Figure 3

Latent Correlations of a Mental Speed General Factor with WMC and AB.

Figure 4

Correlations of RT Bands obtained in Mental Speed Tasks with WMC and AB. Factor (CFA) corresponds with a latent factor obtained in a confirmatory factor analysis using the three stimulus materials as observed indicators.

Figure 5

Parameters of the ex-Gaussian parameterization fitted to the Substitution tasks as predictors of WMC and AB. Significant parameters are displayed in black font.