Biomedical subjects

R Rothkegel

Publications and source records attributed to R Rothkegel.

3 recordsLinked to original sources

PubMed2000

Subitizing and its subprocesses.

When people are presented with small sets of elements such as dots they can very easily determine their number. This ability has been called subitizing. The present paper reports results from four experiments. The discussion focuses on the question whether one or two psychological processes have to be assumed for this task of subitizing. Taken together our results support the two-process theories. In particular, a distinction between a process of separation and a process of enumeration is suggested. Experiments 3 and 4 support the canonical pattern hypothesis. Canonical patterns are processed substantially faster than noncanonical patterns. Furthermore, if a complex pattern can be broken down into small canonical patterns, then participants follow a partition and add strategy.

Analysis of Variance↗

PubMed1999

AppleTree: a multinomial processing tree modeling program for Macintosh computers.

Multinomial processing tree (MPT) models are statistical models that allow for the prediction of categorical frequency data by sets of unobservable (cognitive) states. In MPT models, the probability that an event belongs to a certain category is a sum of products of state probabilities. AppleTree is a computer program for Macintosh for testing user-defined MPT models. It can fit model parameters to empirical frequency data, provide confidence intervals for the parameters, generate tree graphs for the models, and perform identifiability checks. In this article, the algorithms used by AppleTree and the handling of the program are described.

Cognition↗

PubMed1997

Measures of spatial memory and routes of learning.

Spatial memory was investigated in two experiments by direct methods. Methods included scaling of distances, estimation of bearings, and positioning of objects. Participants learned small-scale configurations under different orders of presentation. In Exp. 1, routes included a shortest path, i.e., a traveling salesman solution, a random sequence, and a path that maximized distances. In Exp. 2, spatial and temporal distances varied independently. It was analyzed whether the different methods yielded the same information. For bearing estimates a new scaling procedure was developed. Computations resulted in two-dimensional Euclidean solutions in close correspondence with the stimulus configuration. In addition, solutions showed an effect of temporal conditions of learning.

Attention↗