Determination of discount functions in rats with an adjusting-amount procedure
Determination of discount functions in rats with an adjusting-amount procedure
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DOI：
10.1901/jeab.1997.67-353
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发表时间：
1997-05-01
影响因子：
2.7
通讯作者：
Seiden, LS
中科院分区：
文献类型：
--
作者：
Richards, JB;Mitchell, SH;Seiden, LS
采用调整量程序来衡量延迟对增强剂价值的贴现。八只老鼠在即刻给不同量的水和延迟一段时间后给固定量的水之间进行选择。根据老鼠先前的选择，系统地调整了即刻的水量。这一程序被用来确定每只大鼠选择即刻量和延迟量的频率相等的无差别点。在这个无差别点处的即时水量被用来估计延迟水量的值。在试验一中，对固定增强剂(L在0、2、4、8或16天后送水100亩)延迟的日变化效应进行了试验。在这种情况下，在每次60次试验的前30次试验中，大鼠达到无关点。实验二考察了缺水程度对延迟贴现的影响。改变缺水程度影响反应速度，但不影响延迟折扣。在试验3中，试验了不同延迟量(100亩、150亩和200亩L)对水稻生长发育的影响。虽然这种差异没有达到统计学意义，但对于较大的增强体，贴现函数有比较小的增强体陡峭的趋势。在所有三个实验中，所获得的贴现函数都可以用双曲线函数很好地描述。这些实验表明，调量程序为测量延迟对增强剂价值的贴现提供了一种有用的工具。
An adjusting-amount procedure was used to measure discounting of reinforcer Value by delay. Eight rats chose between a varying amount of immediate water and a fixed amount of water given after a delay. The amount of immediate water was systematically adjusted as a function of the rats' previous choices. This procedure was used to determine the indifference point at which each rat chose the immediate amount and the delayed amount with equal frequency. The amount of immediate water at this indifference point was used to estimate the value of the delayed amount of water. In Experiment 1, the effects of daily changes in the delay to the fixed reinforcer (100 mu l of water delivered after 0, 2, 4, 8, or 16 s) were tested. Under these conditions, the rats reached indifference points within the first 30 trials of each 60-trial session. In Experiment 2, the effects of water deprivation level on discounting of value by delay were assessed. Altering water deprivation level affected the speed of responding but did not affect delay discounting. In Experiment 3, the effects of varying the magnitude of the delayed water (100, 150, and 200 mu l) were tested. There was some tendency for the discounting function to be steeper for larger than for smaller reinforcers, although this difference did not reach statistical significance. In all three experiments, the obtained discount functions were well described by a hyperbolic function. These experiments demonstrate that the adjusting-amount procedure provides a useful tool for measuring the discounting of reinforcer value by delay.