Fig. 7. Parameters of the function relating novelty response and the change in image contrast (PP). (A) Results obtained in a single fish using different increase-and-hold patterns of stimulation, where the amplitude of the novelty response (I/I₀) is plotted as a function of PP for three different baseline periods. Symbols indicate the duration of the baseline period: 2 s (open squares; 44 EODs), 10 s (closed circles; 210 EODs), 29 s (open circles; 600 EODs). Trial duration was the same in all experiments (30 s). Note that the scaling constant (the slope of the line fitting the data) increases as a function of the duration of the baseline period. (B) The scaling constants, obtained in the same way in three fish, are plotted as a function of the number of baseline local electric organ discharges (LEODs) (r²=0.88, P<0.01, N=8). Each symbol corresponds to a different fish. (C,D) Threshold₅₀ was studied in three fish for different baseline periods. Probability of evoking novelty responses is plotted as a function of PP. In (C) data obtained from a single fish using baselines of 2 s (closed triangles), 10 s (closed circles) and 29 s (open circles) are compared. In (D) the results were obtained using extreme baseline periods; 0.5 s (open symbols) and 29 s (filled symbols) are compared. Each symbol shape corresponds to a different fish (N=3).

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