Shaping Brain and Behaviour: Investigating the Properties and Electrophysiological Correlates of Reinforcement

Recently, the fundamental definition of reinforcement has been challenged. The traditional account holds that reinforcement strengthens preceding behaviour. The challenging theory suggests that reinforcers guide behaviour by their discriminative properties signposting the current environmental contingencies. This thesis aimed to determine whether the traditional strengthening theory or the signalling account is the more accurate and useful framework for understanding reinforcement. Behavioural choice procedures were integrated with the analysis of Event-Related Potentials (ERP) to test these theories with respect to their predictions for both conditional and direct reinforcement. The integration of ERP analysis enabled the investigation of how neural correlates of reinforcement relate to the environment and behaviour, helping to constrain potential mechanisms of reinforcement. Chapter Two used a two-alternative choice procedure to establish that the reward stimulus used throughout this thesis was indeed a reinforcer according to both definitions. This was crucial for the validity of all the experiments. Furthermore, a within-subject relationship between choice preference and the Feedback Negativity was quantified. This relationship was better described by the signalling account. Chapter Three provided the first demonstration of the effect of contingency on reinforcer-related potentials. This was an important finding as contingency is a critical component of the signalling account of reinforcement, whereas the strengthening account focuses on temporal contiguity as the main determinant of reinforcement. Chapter Four directly tested the predictions of the signalling and strengthening accounts by arranging a probabilistic sequence of reinforcers. The sequence was such that the last two reinforcers predicted the source of the next reinforcer. Both choice preference and reinforcer-evoked potentials were modulated by the arranged conditional probability, in accordance with the signalling theory. Chapter Five built on Chapters Four and Three, assessing the joint predictions of the information-theoretic concept of contingency and the signalling account, by examining conditional reinforcement in a concurrent-chains procedure. Both the choice and the ERP results verified these joint predictions, demonstrating the superiority of the signalling account. Taken together, these results show that the signalling theory is a more accurate and useful explanation of both conditional and direct reinforcement, with the traditional strengthening account irreconcilable with the majority of observations.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Psychology

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

2017

Author dc:creator

• McGill, Stuart

Advisors dc:contributor.advisor

• Corballis, P
• Elliffe, D

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Handle dc:identifier.uri

https://hdl.handle.net/2292/35625

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/35625