Behavior analysts typically teach conditional discriminations in a mixed-trial format but may switch to a blocked-trial format for learners displaying limited acquisition. No known research has shown that mixed-trial methods are more effective or efficient than blocked-trial methods for teaching discriminations, so it is not clear why this format…

Five individuals with autism or other developmental disabilities participated in paired-stimulus preference assessments during repeated baseline probes. All subjects initially showed a pronounced bias by typically selecting the stimulus placed in either the left or right position. Biased responding for 3 subjects was eliminated when training…