Additive and suppressive response summation with a chain schedule.
Rats responded in a two-segment (variable-interval variable-interval) chain schedule. In one experiment, three subjects had either clicker, light, or clicker plus light as terminal-segment stimuli. All three responded at the highest rate when clicker plus light were present, thus showing additive summation. For three other subjects, initial-segment stimuli were either clicker, light, or clicker plus light. Two subjects responded at the lowest rate when clicker plus light were present, thus showing suppressive summation. In a second experiment, three subjects had either clicker, light, or neither clicker nor light as terminal-segment stimuli. None of these subjects showed reliable additive summation. Three other subjects had clicker, light, or neither as the initial-segment stimulus, and all three showed suppressive summation. Additive and suppressive summation both can be demonstrated with chain schedules, but stimulus parameters may be major variables in producing the effect.
Meltzer
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D
Niebuhr
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BR