Triadic distance models can be used to analyse proximity data defined on tr
iples of objects. Three-way symmetry is a common assumption for triadic dis
tance models. In the present study three-way symmetry is not assumed. Triad
ic distance models are presented for the analysis of asymmetric three-way p
roximity data that result in a simultaneous representation of symmetry and
asymmetry in a low-dimensional configuration. An iterative majorization alg
orithm is developed for obtaining the coordinates and the representation of
the asymmetry. The models are illustrated by an example using longitudinal
categorical data.