Evidence for two processes underlying the serial position curve of single- and multi-trial free recall in a heterogeneous group of psychiatric patients: a confirmatory factor analytic study.

The U-shaped serial position curve (SPC) of single-trial free recall is a well-established empirical fact, and there is ample evidence that it is the result of two different memory functions. However, it is insufficiently clear whether the same holds true for the SPC of multi-trial free recall. Free recall test measurements of two large heterogeneous groups of psychiatric patients were subjected to factor extraction using Principal Components Analysis and oblique rotation in two studies. The results of these two experiments show that the SPCs of single- and multi-trial free recall arise from the same two functions i.e. one function underlies the recency part, the other the primacy and middle (prerecency) part. Possible theoretical interpretations are discussed.