On distinguishing human behavior by means of mutual interference

人类表现出各种各样的行为：从简单的、不可避免的反射(即，非故意行为)到行动，即为实现特定目标而表现出的特定意图的行为。在后一种情况下，心理学家有时会区分外部触发的行为和内部发起的行为。这些任务通常分别通过所谓的强制选择任务(刺激决定一个且唯一正确的行动)和自由选择任务(参与者可以在几个同样正确的行动中进行选择)来实现。然而，这一区别的经验证据尚不清楚。在第一个项目阶段，采用双重任务干扰的敏感性来调查这类行为之间的质的差异。研究结果表明：(1)非故意行为不受双重任务干扰的影响，与(易受干扰的)行为有质的区别。(2)两种类型的动作(有时是不同的)都同样容易受到双重任务干扰的影响，因此在性质上没有区别。本项目第二阶段的重点是在一个框架内对强迫和自由选择任务进行概念化，这一框架的灵感来自顺序抽样模型。初步实验表明，在两种类型的任务中，证据都会积累，甚至是以相同的速度积累。然而，这两项任务的不同之处在于它们的非累积时间。这一框架将在几个实验中进一步测试，特别是测试次级双重任务是否影响两个任务的相同组成部分。此外，本研究还探讨了额外的非累积时间在自由选择任务中的作用(以及累积的基础)和各种意图的影响。本项目阶段的结果将有助于澄清强制选择任务和自由选择任务之间的关系，并为随后的项目结果和关于这两种任务类型的文献提供正式模型的基础。

Humans show enormous varieties of behavior: They range from simple, unavoidable reflexes (i.e., non-intentional behavior) to actions, that is, behavior that is shown with a particular intention to achieve a certain goal. In the latter case, psychologists sometimes distinguish externally-triggered and internally-initiated actions. These are operationalized most often with so-called forced-choice tasks (where a stimulus determines the one and only correct action) and free-choice tasks (where the actor can choose among several equally correct actions), respectively. The empirical evidence for this distinction, however, is unclear.In the first project-phase the susceptibility to dual-task interference was taken to investigate qualitative distinctions between such types of behavior. The results allow the following conclusions: (1) Non-intentional behavior is not susceptible to dual-task interference and thus differs qualitatively from (interference-susceptible) actions. (2) Both (sometimes distinguished) types of actions are equally susceptible to dual-task interference and thus do not differ qualitatively. The focus of the present second project-phase is the conceptualization of forced-and free-choice tasks within one framework, which is inspired by sequential sampling models. Pilot experiments suggest that in both types of tasks evidence accumulates, and even with the same rate. However, both tasks differ in their non-accumulation times. This framework will be tested further in several experiments, in particular to test whether a secondary dual-task affects the same components of both tasks. Additionally, the function of the additional non-accumulation time in free-choice tasks (and thus the basis of accumulation) and the effects of various kinds of intentions are investigated.The results of this project-phase will (1) help to clarify the relation of forced- and free-choice tasks, and (2) provide the basis for a subsequent formal modelling of the projects results and the literature on both task-types.