Table 2. Group average and standard deviations of hole-entering response rates for baseline (BL) and FI conditions.

Group	BL Mean	FI Mean	Mean Difference	BL SD	FI SD	SD Difference
0-0-X	6.89	8.46	1.57	2.46	2.51	0.05
0-15-X	6.22	10.36	4.14	1.77	6.02	4.24
0-30-X	6.82	7.00	0.18	2.11	3.63	1.52
0-60-X	6.88	6.66	−0.22	2.23	3.04	0.80
0-120-X	5.76	6.08	0.32	2.05	3.53	1.48

Response rates are expressed in responses per minute. Baseline group averages imply roughly equal groups prior to the condition change. The 0-15-X group's standard deviation (SD) indicates non-homogeneous data during the FI condition.