Modeling External and Internal Influences on Task Choice

描述(申请人提供)：在允许多种行为路径的环境中，人类值得注意的是他们适应内部目标或外部刺激变化的能力。面对相互竞争的可能行动，选择特定的行为是行政控制的职权范围(Logan，1985)。这项研究的总体目标是考察影响一个人选择执行特定任务的因素，并在多任务环境中开发一个正式的任务选择模型。这项研究将使用最近开发的自愿任务转换(VTS)范式，在该范式中，受试者选择在多任务环境中的每个实验中执行哪项任务(Arrington&Logan，2004a；2005)。与标准任务切换范式不同，VTS允许研究人员在涉及任务选择和任务切换时的性能的环境中检查控制过程，从而提供了一种新的执行控制措施：任务选择。本研究的三个项目的具体目的是考察外部刺激和内部目标设置对任务选择的影响。项目1通过参数操作两个不同的时间间隔来隔离外部和内部对任务选择的影响。提供每项任务的刺激的开始时间将被操纵，以检查外部刺激可用性对任务选择的影响；而试验之间的时间量将被操纵，以检查准备时间对任务选择的影响，允许自上而下地设定目标。项目2和3进行了新的经验性调查，以测试任务选择方面的内部控制的具体组成部分。项目2检查对象选择的作用，项目3调查执行每项任务的频率。每个项目都将结合行为数据的收集和认知过程的数学建模，这些认知过程在Logan的执行控制模型(1990)的视觉注意理论(ECTVA；Logan&Gordon，2001)中指导任务选择。在ECTVA中，选择和分类刺激的过程被认为是一场比赛，获胜者由所有可能的分类的处理速度决定。在最简单的水平上，加工速度是两个参数的组合：对特定分类做出反应的偏差和该分类的外部刺激提供的证据。偏差参数是通过执行控制确定的，代表目标设定。证据参数是外部刺激的结果。因此，ECTVA非常适合对影响任务选择的内部和外部因素进行建模。任务选择的正式模型的发展将为意志行为的神经生理学研究提供一个框架，旨在阐明外侧和内侧神经回路的贡献(Haggard，2008)。它还可能进一步了解行为控制缺陷(如额叶损伤、精神分裂症或多动症)特定人群的选择过程。 公共卫生相关性：个人做出的行为选择可能对其身心健康产生重大影响；此外，影响行为控制的障碍对个人和社会都具有重大后果。这项拟议的研究将收集行为数据与数学建模相结合，以检查外部的、基于刺激的因素和内部的目标设定因素，这些因素影响了在多任务环境中执行特定任务的选择。任务选择的正式模型的发展将为推进理论驱动的研究提供一个框架，这些研究是意志行为和涉及行为控制缺陷的精神障碍的神经回路的基础。

DESCRIPTION (provided by applicant): In environments that allow for multiple behavioral paths, humans are noteworthy for their ability to adapt to changes in internal goals or external stimuli. The selection of a particular behavior in the face of competing possible actions is the purview of executive control (Logan, 1985). The overarching goals of the proposed research are to examine the factors that influence a person's choice to carry out a particular task and to develop a formal model of task choice in multitask environments. The research will use the recently developed voluntary task switching (VTS) paradigm, in which subjects choose which task to perform on each trial in a multitask environment (Arrington & Logan, 2004a; 2005). Unlike standard task switching paradigms, VTS allows the researcher to examine control processes in an environment that involves selection of a task as well as performance when switching tasks, thus providing a new measure of executive control: task choice. The specific aims of the three projects in the proposed research are to examine the influences of external stimuli and internal goal setting on task choice. Project 1 isolates external and internal influences on task choice by parametrically manipulating two different timing intervals. The onset time for the stimuli that afford each task will be manipulated to examine the effect of external stimulus availability on task choice; while, the amount of time between trials will be manipulated to examine the effect of preparation time, allowing for top-down goal setting, on task choice. Projects 2 and 3 follow up with new empirical investigations developed to test specific components of internal control over task choice. Project 2 examines the role of object selection and Project 3 investigates the frequency with which each task is to be performed. Each of the projects will combine collection of behavioral data and mathematical modeling of the cognitive processes that guide task choice within Logan's model of Executive Control of Bundesen's (1990) Theory of Visual Attention (ECTVA; Logan & Gordon, 2001). Within ECTVA, the process of selecting and categorizing a stimulus is conceived of as a race with the winner determined by the processing rates for all possible categorizations. At the simplest level, the processing rate results from a combination of two parameters: a bias to respond with a particular categorization and the evidence provided by the external stimulus for that categorization. The bias parameter is determined through executive control and represents goal setting. The evidence parameter results from the external stimuli. Thus, ECTVA is ideally suited for modeling the internal and external factors influencing task choice. The development of a formal model of task choice will provide a framework for research into the neurophysiology of volitional behavior aimed at elucidating the contributions of lateral and medial neural circuits (Haggard, 2008). It may also further understanding of choice processes in specific populations with deficits in behavioral control (e.g. frontal lobe damage, schizophrenia, or ADHD). PUBLIC HEALTH RELEVANCE: The behavioral choices that individuals make can have significant impact on their physical and mental health; furthermore, disorders affecting behavioral control have dramatic consequence for both individuals and society. The proposed research combines collection of behavioral data with mathematical modeling to examine external, stimulus-based factors and internal, goal-setting factors that influence the choice to perform a particular task in a multitask environment. The development of a formal model of task choice will provide a framework for advancing theoretically-driven research into the neural circuits that underlie volitional behavior and mental disorders involving deficits in behavioral control.