University of Guadalajara, Guadalajara, Jalisco, Mexico.
J Exp Anal Behav. 2009 May;91(3):293-317. doi: 10.1901/jeab.2009.91-293.
To examine extended control over local choice, the present study investigated preference in transition as food-rate ratio provided by two levers changed across seven components within daily sessions, and food-amount ratio changed across phases. Phase 1 arranged a food-amount ratio of 4:1 (i.e., the left lever delivered four pellets and the right lever one pellet); Phase 2 reversed the food-amount ratio to 1:4, and in Phase 3 the food-amount ratio was 3:2. At a relatively extended time scale, preference was described well by a linear relation between log response ratio and log rate ratio (the generalized matching law). A small amount of carryover occurred from one rate ratio to the next but disappeared after four food deliveries. Estimates of sensitivity to food-amount ratio were around 1.0 and were independent of rate ratio. Analysis across food deliveries within rate-ratio components showed that the effect of a small amount was diminished by the presence of a large amount-that is, when a larger amount was present in the situation (three or four pellets), the value of a small amount (one or two pellets) became paltry. More local analysis of visits to the levers between food deliveries showed that postfood visits following a large amount were disproportionately longer than following a small amount. Continuing food deliveries from the same source tended to make visits less dependent on relative amount, but a discontinuation (i.e., food from the other lever) reinstated dependence on relative amount. Analysis at a still smaller time scale revealed preference pulses following food deliveries that confirmed the tendency toward dependence on absolute amount with continuing deliveries, and toward dependence on relative amount following discontinuations. A mathematical model based on a linear-operator equation accounts for many of the results. The larger and longer preference following a switch to a larger amount is consistent with the idea that local preference depends on relatively extended variables even on short time scales.
为了检验对局部选择的扩展控制，本研究在每日的实验中，通过七种成分改变两个杠杆提供的食物率比，并通过相位改变食物量比，来考察了选择在食物率比转换时的偏好。在第一阶段，食物量比安排为 4:1（即左边的杠杆提供四个食物丸，右边的杠杆提供一个食物丸）；在第二阶段，食物量比反转到 1:4；在第三阶段，食物量比为 3:2。在相对扩展的时间尺度上，对数反应比与对数率比之间的线性关系很好地描述了偏好（广义匹配律）。下一个率比会受到上一个率比的少量影响，但在四次食物传递后这种影响就消失了。对食物量比的敏感性估计值约为 1.0，且独立于率比。在分析每个率比成分内的食物传递时，结果表明小量的影响会被大量的影响所减弱——即当一种较大的量存在于情境中时（三个或四个食物丸），较小量（一个或两个食物丸）的价值就变得微不足道。对食物传递之间杠杆访问的更局部分析表明，大量食物之后的食物后访问时间比小量食物后更长。持续来自同一来源的食物传递往往会使访问不太依赖于相对量，但中断（即来自另一个杠杆的食物）会重新使访问依赖于相对量。在更小的时间尺度上进行分析时，发现食物传递后有偏好脉冲，这证实了持续传递时偏好依赖于绝对量，而中断传递时偏好依赖于相对量的趋势。基于线性算子方程的数学模型可以解释许多结果。与连续传递时的绝对量依赖关系相比，切换到较大量时偏好更大、更长，这与局部偏好取决于相对扩展变量的观点是一致的，即使在短时间尺度上也是如此。
