Choi Hoon, Watanabe Takeo
Department of Psychology, Boston University, Boston, MA, USA.
Learn Percept. 2009 May 7;1(1):89-98. doi: 10.1556/LP.1.2009.1.7.
How does the brain determine what to learn and what not to learn? Previous studies showed that a feature or stimulus on which subjects performed a task was learned, while the features or stimuli that were irrelevant to the task were not learned. This led some researchers to conclude that attention to a stimulus was necessary for the stimulus to be learned. This thought was challenged by the discovery of a task-irrelevant perceptual learning, in which learning occurred by mere exposure to the unattended and subthreshold stimulus. However, this exposure-based learning does not necessarily indicate that all presented stimuli are learned. Rather, recent studies showed that the occurrence of this learning was very selective for the following new findings: unattended stimulus learning occurred only (1) when the unattended stimulus was associated temporally with the processing of an attended target, (2) when the unattended stimulus was synchronously presented with reinforcers, such as internal or external rewards, and (3) when the unattended stimulus had subliminal properties. These selectivities suggest some degrees of similarity between task-relevant and task-irrelevant perceptual learning, which has been the motivation for making a united model in which both task-relevant and task-irrelevant learning are formed with similar or same mechanisms.
大脑如何决定学习什么和不学习什么？先前的研究表明，受试者执行任务时所涉及的特征或刺激会被学习，而与任务无关的特征或刺激则不会被学习。这使得一些研究人员得出结论，对刺激的关注是刺激被学习的必要条件。一项与任务无关的知觉学习的发现对这一观点提出了挑战，在这种学习中，仅仅通过接触未被注意到的阈下刺激就会发生学习。然而，这种基于接触的学习并不一定表明所有呈现的刺激都会被学习。相反，最近的研究表明，这种学习的发生对以下新发现具有很强的选择性：未被注意到的刺激学习仅在以下情况下发生：(1) 未被注意到的刺激在时间上与被注意到的目标的处理相关联；(2) 未被注意到的刺激与强化物（如内部或外部奖励）同步呈现；(3) 未被注意到的刺激具有阈下特性。这些选择性表明任务相关和任务无关的知觉学习之间存在一定程度的相似性，这促使人们建立一个统一的模型，在这个模型中，任务相关和任务无关的学习是由相似或相同的机制形成的。
