Short-term memory (STM) in a "minimal" paired-associate (PA) task was investigated by presenting Ss with two successive picture-trigram (Exp. 1) or picture-letter (Exp. 2) PA units. Affective content of one stimulus term was pleasant (P) and the other was unpleasant (U). After either a 3-, 9-, or 15-sec. retention interval, during which Ss engaged in number tracking, one of the two PA units was tested for recall. Recall of U units was inferior to P units for both response classes. However, with letters recall of P was higher than U at immediate recall (3 sec.), but affect did not differentially influence recall at 9 and 15 sec. With trigrams, differential recall extended from 3-15 sec., but differences between P and U were attenuated. These findings suggest that the differential influence of affect on STM varies directly with task difficulty, represented in the PA task by differences in response availability.