Introduction to the Rasch Poisson Counts Model: An R Tutorial

The Rasch Poisson Counts Model is the oldest Rasch model developed by the Danish mathematician Georg Rasch in 1952. Nevertheless, the model has had limited applications in psychoeducational assessment. With the rise of neurocognitive and psychomotor testing, there is more room for new applications of the model where other item response theory models cannot be applied. In this paper, we give a general introduction to the Rasch Poisson Counts Model and then using data of an attention test walk the reader through how to use the “lme4” package in R to estimate the model and interpret the outputs.

Saccadic eye movement analysis as a measure of drug effects on human psychomotor performance

Analysis of human horizontal saccadic eye movements can provide measurements of central nervous system depression and stimulation. Effects on saccadic eye movements have been observed in normal volunteers with barbiturates, benzodiazepines, opiates and related compounds, carbamazepine, amphetamine and ethanol. A suite of programmes have been developed to allow the generation, collection and analysis of saccadic eye movements using a CBM 3032, 8032 or BBC B microcomputer. The system allows almost continuous sampling and rapid analysis of movements.