Final answer:
The control subjects in study 2 could develop respiratory changes as an additional conditioned response, inferring from the repeated mention of increased minute respiration.
Step-by-step explanation:
Based on the passage, the control subjects in study 2 could develop respiratory changes as an additional conditioned response. This conclusion can be drawn from the repeated mention of increased minute respiration, which is associated with changes in breathing pattern often seen in response to certain stimuli or conditions in an experiment. This physiological change is distinct from fight-or-flight responses mentioned such as pupil dilation or increased oxygen to the lungs, which often include increased heart rate and blood pressure but not specifically lowered blood pressure or enhanced memory.