What is Psychophysics and what does it tell us? A quick intro

I came across the term in a new book by Frank Wilczek called ‘The Ten Keys of Reality’. which was just released this month. I’ve been a fan of the author since reading ‘The Beautiful Question’ – a wonderful book about the deep patterns in nature (you can read more on my thoughts about it here).

A Nobel Prize winning physicist, Wlczek has a treasure trove of knowledge to share which he does so eloquently and simply. I stopped in my tracks at the mention of ‘psychophysics’. It sounds like exactly the kind of inquiry into humans that Recknsense is interested in. You won’t be surprised to hear it’s a combination of Psychology and Physics. It’s actually a branch of psychology that looks at the physical stimulus specifically. The example in the first few pages of Wilczek’s book blew me away. It described an experiment where subjects were hooked up to a brain scanner and using a technique called transcranial magnetic stimulation (TMS) they were able to have their left and right brain motor centers stimulated. The subjects were asked to decide to twitch their right or left wrist and then act it out. The experiment was able to predict the choice of which wrist would be twitched before the subject moved.

Even more astounding was that there was a way for the experimenter to affect the stimulation so that the subject’s choice could be overridden. Yes this sounds like mind control! When subjects were asked why they twitched they did not exclaim that a mysterious force had drove them to it – they just said they changed their mind.

Digging deeper

The definition of psychophysics is that it ‘quantitatively investigates the relationship between physical stimuli and the sensations and perceptions they produce.’ It’s not new. It helps explain some things about humans e.g. how we’re able to fill in the blanks in audio and video perception because of ‘lossy compression’.

The topic of perception, consciousness and how humans understand our reality is something that has interested me ever since I started to read about quantum theory. I’ve written about quantum physics and the possible connections with the brain, so naturally this branch of science caught my attention.

Weber’s law

In my brief research I came across the concept of Weber’s law which is described in this article as ‘the oldest and most firmly established law in psychophysics’.  Discovered by German physicist Ernst Heinrich Weber, the law observes that the probability that a person will correctly detect a weight is heavier than another only depends on the ratios of those weights. This concept helps define the field of psychophysics further – it’s about the physical stimuli we experience and the sensations they invoke in our mind. There is a science to it and Weber’s law includes mathematical calculations.

This article describes a research study which extended Weber’s law by figuring out that time was an important factor. From the experiment (conducted on rats), it turned out the time taken to make a decision impacted how accurate it would be. In the case of that study, it wasn’t weight difference but audio perception that was being tested i.e. the loudness of sounds. The louder the sounds being compared, the quicker the decision on perception was made.

Studies and experiments

I came across a new study that is being developed which tries to answer the question of why gamers invert their controls. The question is a perfect one for psychophysics as it takes a physical action and looks at the psychological impact – or in this case a phenomenon that occurs which appears to make no sense. For some reason gamers will often push their joystick down when they want to move up – they invert their controls. You can find out more about the origins of the study here.

There is even an open source tool called SimplePhy for ‘quick online perception experiments’ specifically for psychophysics. It’s a recent development conceived because of Covid’s restrictions in the ability to conduct research via traditional methods. I haven’t used it so can’t attest to how good it is but the fact it exists shows the growing need to understand more on this science.

It’s not just in tech and the possibly scary applications which could originate there, there are other places where psychophysics could take root. Using psychophysic based experiments, we can get a better understanding of mental health. For example this study on schizophrenia investigated beyond genetics to see the link between certain brain patterns in patients.

How Psychophysics might be applied

The science of psychophysics exists alongside Neuroscience which is the more well known of the fields. To gain a comprehensive understanding of what is really happening we need to understand how neurons in the brain contribute to the mix. What exactly do our neurons do when we behave a certain way upon physical stimuli in addition to our perception of it?

As we move towards human centric designs and artificial intelligence that aims to be more human like, we will see the field of psychophysics grow. The understanding of perception, the drivers for it and how we make decisions as a result are going to be very important. Tech companies are bound to be racing to find connections that they could apply. Let’s hope it’s not applied unethically which is even more reason for us techies to learn more about ethics and be aware.

We’ve become more accustomed to reacting primarily to sound, visuals and touch rather than having the patience to read long form. Advertisers know that. Being able to understand the link between the senses and our perception (and consequently our behavior) is all the more valuable.

Psychophysics is a science we may hear a lot more about in the future. It represents an exciting and intriguing blend of sciences that helps us understand more about ourselves. In the process we may be able to apply it for good use. Now I’m going back to reading Wilczek’s book – I’m only at chapter 1!

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