Displacement acts, once a hot topic in ethology, but wrapped in silence for two decades since, have recently been suggested to indicate and relax social tension (Maestripieri et al., 1992; Wiepkema, 1987). The first of these contentions seems to be in contradiction with some of the classical ethological studies of displacement behaviour, in particular those supporting the disinhibition hypothesis, since the latter would not predict any positive correlation between amount of tension (i.c. intensity of the conflict) and the occurrence of (...) displacement acts.A critical examination of these studies reveals that a positive correlation of the sort has been found, but that proponents of the disinhibition hypothesis tried to explain it in terms of their own model, rather than taking it at its face value. (The reason for this is that they viewed it as pleading for the surplus hypothesis which they rejected). It can be shown that at least some of their explanations are grounded on assumptions which are arbitrary. Also, the disinhibition hypothesis does not account for the occurrence of displacement behaviour in contexts with tension but without conflict. (shrink)