Information Aggregation under Computational Complexity

Information Aggregation under Computational Complexity (HREC 1852128.2)


We aim to examine markets’ ability to aggregate information into market prices when individual trading decisions are complex. We hope to provide a better understanding of how problem complexity impacts information aggregation in financial markets. For this purpose, we rely on a market experiment where participants trade claims to the solution of instances of the so-called knapsack decision problem (see below). Participants need to be between 18 and 35 years old, and to not have previously taken part in a “knapsack” (“Complex decisions”, or “Decision Pathways”) experiment with the BMM Lab.

What will I be asked to do?

Should you agree to participate, you will be asked to carry out a computer-based task in a behavioural testing lab. You will be solving a set of combinatorial decision problems, while trading securities in an online financial market. The decision problems consist of different instances of the knapsack problem, where items of different values and weights are to be added to a weight-constrained knapsack of prespecified minimal value. The securities’ payoff will depend on the solvability of a given instance. Trading will take place through an online market platform.

The estimated time of commitment will be about 180 minutes. Participation in this study is completely voluntary and the information collected will remain confidential. Your time and effort will be compensated by a cash payment partly depending on your performance in the experiment. Each participant will earn between $20 – $80 at the end of the experimental session, where payment will vary according to performance in the tasks. The average/expected payoff is $50. A participant who decides not to participate at any point in the session will be paid $10, as a show-up fee.

What are the possible benefits?

The results of this study will provide novel insights into how problem complexity affects both human decision-making and information aggregation within financial markets.

What are the possible risks?

There are no material risks beyond the variation in performance-based payments.

Do I have to take part?

No. Participation is completely voluntary. You are able to withdraw at any time. Should you wish to withdraw at any stage, or withdraw any unprocessed data you have supplied, you are free to do so without prejudice, and any potential conflicts of interest arising. If you are a student of the above researchers, participating or withdrawing will not affect your grades in any way.

Will I hear about the results of this project?

Results of the study will be available from the researchers’ websites, be presented at conferences and be published in peer-reviewed journals.

What will happen to information about me?

This is an anonymous study. We will protect the confidentiality of your trading and responses to the fullest possible extent, within the limits of the law. Only participant codes will be used in storage of the data. The trading and response data will be kept securely in the Department of Finance for a minimum of five years from the date of publication.

Where can I get further information?

If you would like more information about the project, please contact the researchers at or 03 9035 9950.

Who can I contact if I have any concerns about the project?

This research project has been approved by the Human Research Ethics Committee of The University of Melbourne. If you have any concerns or complaints about the conduct of this research project, which you do not wish to discuss with the research team, you should contact the Manager, Human Research Ethics, Research Ethics and Integrity, University of Melbourne, VIC 3010. Tel: +61 3 8344 2073 or Email: All complaints will be treated confidentially. In any correspondence please provide the name of the research team or the name or ethics ID number of the research project.

How Do I Agree to Participate?

If you decide to participate, please sign up for an experimental session here.

Human ethics approval

This study has been approved by the University of Melbourne Human Research Ethics Committee (HREC: 1852128.2).

Brain, Mind and Markets Lab
Department of Finance
The University of Melbourne
Victoria 3010
Phone: +61 3 9035 9950