Fig. 4.

Response to sound during training. Bars show the proportion responding in the paired (red) and unpaired (gray) groups. Dark portions indicate a strong PER; light portions indicate a weak PER. The no-reward group (not shown) was indistinguishable from the unpaired group. Curves show the response probabilities for each group predicted by our GEE model; dashed lines are the no-learning rates (equal to the initial response rate). For each intensity and test condition, we report the number of flies (N), the value and standard error of the GEE regression slope parameter (β_T for the test paired condition; β_C for the control unpaired condition) and the P-value for the regression parameter. The last two points (T1 and T2) are tests of retention in which only the sound was presented.