An Investigation of the Slope Parameters of Reaction Times and P3 Latencies in the Sternberg Memory Scanning Task - A Fixed-Links Model Approach.

Henrike M Jungeblut,Christoph Löffler,Dirk Hagemann,Anna-Lena Schubert

doi:10.5334/joc.158

Abstract

The speed of short-term memory scanning is thought to be captured in the slope of the linear function of mean reaction times (RTs) regressed on set size in the Sternberg memory scanning task (SMST). Individual differences in the slope parameter have been hypothesized to correlate with general intelligence (g). However, this correlation can usually not be found. This present study chose a fixed-links model (FLM) approach to re-evaluate the RT slope parameter on a latent level in a sample of 102 participants aged 18 to 61 years who completed the SMST with set sizes 1, 3, and 5. The same was tried for P3 latencies to investigate whether or not both parameters measure the same cognitive processes in the SMST, and to assess the usability of both slopes to predict g. For RTs, a linear increase with set size was found. The slope of mean RTs correlated with g on a manifest level already. The FLM approach could better reveal this relationship with the correlation between the slope and g being substantially higher. For P3 latencies, we found no evidence for a linear increase, but a general increase from the smallest set size to the two larger ones. This indicates that RTs and P3 latencies do not measure the same cognitive processes in the SMST. The FLM proved suitable to investigate the association between the speed of short-term memory scanning and intelligence.

Highlights

These findings show that reaction times (RTs) increased with increasing set size, that RTs were negatively correlated with the Berlin Intelligence Structure test (BIS)-scales, and that RTs of less intelligent individuals displayed a steeper trajectory with increasing set size than RTs of more intelligent ones
We found support for earlier findings that RTs in the Sternberg memory scanning task (SMST) increase linearly with set size, that RTs are negatively correlated with g, and that the slope of the linear function of RTs regressed on set size is correlated with g
The results suggest that the process captured by P3 latencies that takes place during the SMST is less affected by the experimental manipulation

Summary

Introduction

The speed of information processing has been proposed as one underlying general feature (Jensen, 2006). We focused on the speed of short-term memory scanning as the feature of the memory scanning process that contributes to interindividual differences in intelligence that, among other processes, gives rise to a single g-factor. The slopes of the resulting linear functions were used to predict intelligence. This allows to see whether the speed of short-term memory scanning differs between individuals of higher and lower general intelligence. The fixed-links model (FLM; introduced by Schweizer, 2006) as a special form of structural equation modeling (SEM) was chosen because earlier research has often failed to correlate the slope parameter with intelligence on a manifest level (Jensen, 1987, 1998)

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