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Measurements at t₁

All the variables of all four groups were tested against the null hypothesis that they were drawn from the same population with a repeated measures MANOVA for the first two periods (pre-test, t₁). In those cases, where the null hypothesis could be rejected at p<0.05 the differences were examined more closely. Four variables had to be taken into consideration (Table 2).

Table 2: Values for those variables, where the null hypothesis that the four groups were drawn from one population could be rejected, averaged over the first two periods. SpAmp - spike amplitude (in arbitrary units; 1 unit = 3.9·10^-14 Nm). SPDur - spike duration. ARot - total amount of arena rotation. QuCh - number of quadrant changes. * - p<0.05; ** - p<0.01; *** - p<0.001.

Due to time constraints, the non-reinforced control groups could not be measured simultaneously with the reinforced group (Table 3). Seasonal influences, for example, may have caused a drop in general activity in the non-reinforced groups. This drop is reflected in the differences in arena rotation and quadrant changes. The effect in spike amplitude is mainly due to the large spikes generated by the standard batch, many of which were conditioned before the other groups. Since spike duration is negatively correlated with spike amplitude (-0.17 at period 8 and -0.22 at period 9, p<0.001 in both periods) the result in spike duration is not surprising. Taken together, the data indicate a decrease in overall strength and activity from the reinforced to the control groups. It has to be emphasized that none of the variables calculated with respect to the behavior in the differently treated (hot/cold) sectors showed any deviation.

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