Nation augmente beaucoup quand les stimuli concrets sont peu discriminables ; c) Les deux effets des variables discriminabilité et compatibilité sur le temps de dénomination peuvent se neutraliser ou se renforcer suivant les caractères des stimuli.In a series of experiments we compare the time of designation (time of verbal reaction to concrete stimuli) and the time of reading (time of verbal reaction to written words). It is found that : 1° The time of designation is longer than the time of reading, and this difference cannot be abolished by training ; 2° The difference between the time of designation and the time of reading increases : a) As a function of the number of alternatives : indeed, the time of reading is very little affected by incertitude, while the time of designation increases as a, function of this factor. The differential effects of the alternatives in designation and in reading may be explained by the variable « compatibility » ; b) As a function of « discriminability » : the time of the reading of words does not vary with their discriminability, while the time of designation increases very much when the concrete stimuli are not easily to be discriminated ; c) The two effects of the variables « discriminability » and « compatibility » upon the lime of designation may neutralize or re-enforce each other depending on the chnracleristics of the stimuli.Fraisse P. Le temps de réaction verbale : I. Dénomination et lecture. In: L'année psychologique. 1964 vol. 64, n°1. p. 21