Mmm-hmmm' and 'good,' both spoken casually, were the reinforcing stimuli. The Ss said 600 words. No reinforcement was given for the first 100 words, reinforcement was given for the selected response-category each time it occurred during the next 300 words and no reinforcement was given during the last 200 words. The median rate of saying words was 19.25 words per min. Ten of the 13 Ss who reported the reinforcing stimulus could not identify correctly the response class reinforced, although 5 of these 10 Ss reported a subclass of or a class partially overlapping the one the E was reinforcing.
S seem to be acting under self-imposed instructions.
Both the class of responses chosen by Greenspoon and the classes chosen in these experiments prove to behave as responses. S may, however, often respond with a subclass of, or a response class partially overlapping with, the class arbitrarily singled out for reinforcement by E. For such Ss, the response is saying a more narrowly specified class of words. Some Ss who were conditioned remained unable to report either the occurrence of reinforcement, or the response-class that they had been giving at an enhanced rate. They had not noticed either the environmental event on which their behavior was conditional, nor that may one response had occurred more frequently than others. Although showing a change in rate, i.e. being conditioned, seems a necessary condition for Ss to report either the reinforcing stimulus or the response-class, the converse is not true.