Modeling External and Internal Influences on Task Choice

描述（由申请人提供）：在允许多种行为路径的环境中，人类因其适应内部目标或外部刺激变化的能力而值得注意。在面对竞争性的可能行动时选择特定的行为是执行控制的范围（洛根，1985）。建议的研究的总体目标是检查影响一个人的选择，以执行特定的任务，并制定一个正式的模型，在多任务环境中的任务选择的因素。这项研究将使用最近开发的自愿任务转换（VTS）范式，其中受试者在多任务环境中选择在每次试验中执行的任务（Arrington & Logan，2004 a; 2005）。与标准的任务切换范式不同，VTS允许研究人员在涉及任务选择以及切换任务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。这三个研究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通过参数化地操纵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。将操纵提供每个任务的刺激的起始时间，以检查外部刺激可用性对任务选择的影响;同时，将操纵试验之间的时间量，以检查准备时间对任务选择的影响，允许自上而下的目标设定。项目2和项目3的后续工作是进行新的实证调查，以测试内部控制对任务选择的具体组成部分。项目2研究对象选择的作用，项目3研究执行每项任务的频率。每个项目将结合联合收割机收集的行为数据和数学建模的认知过程，指导任务选择内的执行控制的Bundesen（1990年）视觉注意力理论（ECTVA;洛根和戈登，2001年）洛根的模型。在ECTVA中，选择和分类刺激的过程被认为是一场比赛，赢家由所有可能分类的处理速率决定。在最简单的层面上，加工率是由两个参数的组合产生的：一个是对特定分类做出反应的偏差，另一个是外部刺激为该分类提供的证据。偏差参数通过执行控制确定，代表目标设定。证据参数由外部刺激产生。因此，ECTVA非常适合于模拟影响任务选择的内部和外部因素。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）。它也可以进一步了解特定人群的选择过程，这些人群具有行为控制缺陷（例如额叶损伤，精神分裂症或ADHD）。 公共卫生相关性：个体所做的行为选择会对他们的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有重大影响。该研究将行为数据的收集与数学建模相结合，以研究影响在多任务环境中执行特定任务的选择的外部、基于刺激的因素和内部、目标设定因素。一个正式的任务选择模型的发展将提供一个框架，推进理论驱动的神经回路的研究，意志行为和精神障碍的基础，涉及行为控制的赤字。

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.