Mechanisms of goal commitment and pursuit

Thesis

In natural environments, most rewards follow a period of pursuit. This requires the ability to plan over multiple steps, as well as the need for commitment to chosen goals. This thesis examines these two components of goal-directed behaviour: planning and commitment.

In the first half of the thesis, I investigate the psychological and neural mechanisms supporting commitment to selected goals. This is addressed using a combination of behavioural modelling, functional magnetic imaging (fMRI), and a study with lesion patients. I propose that commitment is supported by attentional mechanisms which prioritize completion of the chosen goal at the expense of better alternatives. Among healthy people, differences in goal commitment and goal- directed attention are predicted by sustained activity in the ventromedial prefrontal cortex (vmPFC). Damage to the same neural region reduces commitment to goals, which leads to a performance advantage in settings where people tend to over-persist. Nevertheless, it is discussed how seemingly irrational levels of commitment to goals will be beneficial in many environments.

In the latter half of the thesis, I turn to questions of how planning toward goals is affected by medial prefrontal damage, in a population of lesion patients. Two pre-existing paradigms in computational neuroscience are used to dissociate how damage affects the different cognitive components contributing to planning. I find that lesions to medial prefrontal areas impair planning in the more complex setting (the ‘four-in-a-row’ task), but not in a simpler setting (the ‘two-step’ task). Further investigation of the underlying cognitive components suggests that damage affects the capacity to select all the relevant information for planning in complex environments.

Authors: Holton, E

• DOI: 10.5287/ora-eogwap2or
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: persistence; decision making; functional magnetic imaging; lesion patients; goal pursuit
• Subjects: Cognitive neuroscience; Computational neuroscience; Psychology