The research idea
At the Logical Calculus Lab, we aim to understand the cognitive architecture of the human brain and particularly the involvement of logic gates in perceptual decision making and reasoning. To interact with the environment, humans use signals from different sensory modalities like vision, audition, and touch all the time. The central question is how such entirely different signals are flexibly combined in multisensory decisions depending on task demands and subjective goals. We are testing our hypothesis that multisensory decisions involve logic gates like AND, OR, and NOT operations (Otto & Mamassian, 2012) and thereby follow fundamental principles of Boolean algebra.
« The design of the following treatise is to investigate the fundamental laws of those operations of the mind by which reasoning is performed; to give expression to them in the symbolical language of a Calculus, and upon this foundation to establish the science of Logic and construct its method; to make that method itself the basis of a general method for the application of the mathematical doctrine of Probabilities; and, finally, to collect from the various elements of truth brought to view in the course of these inquiries some probable intimations concerning the nature and constitution of the human mind. »
The approach
To investigate multisensory decision making, we are using an approach including different levels of study. On a first level, we use behavioural measures like response times as well as mathematical modelling as methods. The goal is to reveal the cognitive architecture that is involved in solving basic tasks that require a combination of multisensory signals. On a second level, we aim to understand how the cognitive architecture, as revealed by the combined behavioural and modelling approach, is implemented in nervous activity. Does the human brain make use of the powerful Boolean algebra as modern computers do?
« Response time is psychology’s ubiquitous dependent variable. No matter what task a subject is asked to do in an experiment, its completion always takes time. […] If the processing of the mind is highly structured, as most psychologists believe, then different paths through that structure will entail different time courses, and those differences will be reflected in the response times. Thus, perhaps, one can infer back from the pattern of response times obtained under different experimental conditions to the structures involved. »
« Because of the “all-or-none” character of nervous activity, neural events and the relations among them can be treated by means of propositional logic. »
References
Boole, G. (1854). An investigation of the laws of thought: on which are founded the mathematical theories of logic and probabilities (Vol. 2): Walton and Maberly.
Luce, R. D. (1986). Response times: their role in inferring elementary mental organization. New York: Oxford University Press.
McCulloch, W. S., & Pitts, W. (1943). A logical calculus of the ideas immanent in nervous activity. The Bulletin of Mathematical Biophysics, 5(4), 115-133.
Otto TU, & Mamassian P (2012). Noise and correlations in parallel perceptual decision making. Current Biology, 22(15): 1391-1396.
Picture credit
The header images are adapted from McCulloch and Pitts (1943), © Springer