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Category: Thoughts

The Diffusion Model of Decision Making

Sherrington … argued that the nervous system responsible for this simplest class of determinate decision making [harm avoidance] could be … composed of three critical elements: a selective sensory element, … a detector for … events in the outside world…; a selective motor element … that led to the activation of muscles; and a point of contact between these two systems (… the integrative element).[1] A sensor fires when it detect something, however, since they are imperfect (both natural or man-made) an additional element is required to collect evidence over time (integrate) to remove errors and noise from the signal – as in a sequential-sampling model.[2]

These models serve as the basis for more complex discriminating behavioural diffusion models, such as directional motion tracking. Consider a juvenile primate watching its mother walk through long grass: as the adult moves rightward it displaces grass, but the juvenile will also see leftward, upward, and downward movement. To tack its mother, the juvenile must discern which of these multiple movements is the primary movement.

Diffusion models add an integration step to collect the relative difference between two options and trigger an action only when the difference exceeds a threshold. Diffusion models have accurately accounted for the observed reaction times and accuracy in experiments compared to accumulator and race models.[2] Diffusion models can also account for the fast erroneous actions which have been experimental observed.[2] Diffusion models using the relative difference implicitly treat evidence for one alternative as evidence against another alternative preventing the errors of multiple conclusions and race-conditions possible in accumulator and counter models which do not have mutual inhibition.[2]

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“Do people have Free Will, or is this universal belief an illusion? Is neuroeconomics the death of Free Will?”

The following text is my 500 word response to the above essay question for the course Introduction to Neuroeconomics: How the Brain Makes Decisions on Cousera.

‘Cogito, Ergo Sum’ wrote René Descartes — ‘I think, therefore I am’. His rationalist argument was that the only we could trust was our conscious thoughts — our “inner-voice”. He argued our senses could be deceiving us, positing that we cannot know a demon is not deceiving us with false inputs — as in the “The Matrix”. His refutation of empiricism is a central text in the historical belief of dualism — i.e. that the human mind is separate from the body; that we are the “Ghost in the Machine”. [1]

Subsequent research has advanced our understanding of ourselves beyond the ancient guesses about the nature of thought. The physicalist paradigm assumes that all that exist is built upon the physical world and its interactions. [2] This paradigm assumes that human consciousness is a manifestation of processes running in our physical bodies, on the nervous system and under the influence of our endocrine system. [5] The physicalists accept emergence as an ontological reality and that our consciousness emerges out of the interactions between our neurons. [6]

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Growth Summary

Although the previous post can be useful to see the detail, 6000+ entries is too much.

For a taste here are the top three (and there are some surprises in the rest)

Riverstone – Marsden Park 134,633

Cobbitty – Leppington 10,5314

Rouse Hill – Beaumont Hills 61,130

So after the fold is the data summarized to SA2 – usual a classification of several suburbs.

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