Leader, G., Barnes, D., & Smeets, P. (1996). Establishing equivalence relations using a respondent-type training procedure. The Psychological Record, 46, 685-706.
The authors (researchers at the National U of Ireland, U Coll, Dept of Applied Psychology, Cork, Ireland) conducted n3 experiments, 35 adults across 7 experimental conditions were exposed to a respondent-type training procedure in which arbitrary stimuli (i.e., nonsense syllables) were presented. Ss demonstrated equivalence responding after 2, 3, or 4 exposures to the training and testing. The remaining 6 conditions showed that the effectiveness of the respondent-type training procedure in producing equivalence responding was dependent upon (1) the presence of longer between-pair-delays relative to the within-pair-delays and (2) the sequence in which stimulus pairs were presented.