McSweeney, F. K., & Swindell, S. (1999).
Behavioral economics and within-session changes in responding.
Journal of the Experimental Analysis of Behavior,
72, 355-371.
Pigeons and rats responded on fixed-ratio schedules with
requirements ranging from 5 to 120 responses. Consistent with
past results from several schedules and procedures, responding
usually changed systematically within experimental sessions. The
within-session changes were usually larger and were less
symmetrical around the middle of the session for schedules that
provided higher, rather than lower, rates of reinforcement. These
results suggest that similar variables contribute to
within-session changes in responding under different schedules.
When an economic demand function was fit to the data, the
intensity and elasticity of demand for food and the percentage of
the variance accounted for decreased within sessions, although
the trend for elasticity did not reach statistical significance
for pigeons. These results suggest that relatively short sessions
should be used to study economic demand in open economies and
that demand may differ at different times in a session and in
sessions of different lengths. Within-session changes in
intensity, but not necessarily elasticity, of demand are
consistent with behavioral economic theories.
Key words: within-session patterns of responding, demand curves,
fixed-ratio schedule, key peck, lever press, pigeons, rats