William T. Powers (1926-2013) Visionary, collaborator & friend

A theory ahead of its time?

In 1973, William T. Powers published 'Behavior: The Control of Perception'. The book formalised the theory he had been developing since the 1950s, andnow it is unifying the physical, life and social sciences.

PCT provides a theory about how human beings and other living systems work – how they control what matters to them. Take a look at the video below to get started...

You can also try out a whole range of interesting ways to illustrate perceptual control on Gary Cziko's website.



This website gives you a glimpse at what a theory called PCT can do to help explain these things, and many, many more...

The idea is simple.

You don’t have to pay for it. It’s for everyone to use.


England Riots - Control & Purpose


In news reports of interviews, people are saying that the rioters are 'out of control', that police need to 'regain control' and that the longer term cause is a lack of 'sense of purpose' in our youth. But what is 'control' and 'purpose' and how can we act to make a difference? Warren Mansell has recently produced a statement on this topic based on PCT. For a full PCT approach to understanding rioting, see McPhail (2005).



The International Control Systems Group Conference 2010 took place at the University of Manchester, UK on Saturday 24th July.

The following papers are available online:

Fred Good - A Connected School

Bill Powers - The Tank that Filled Itself

McClelland & Worthington - Buying & Selling Simulation

Carey - A Right Turn for Researchers

Finally, please click here to read Kieran Lord's review of the conference.

The proceedings of the 2007 CSG conference at University of Manchester are available here.

PCTWeb has been running since 2009 and receives over 2000 visits per month. The current data for today, yesterday and the total visits since February 2012 are:

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Join a Public List...

If you use PCT in your work or studies then please sign up to our public list by clicking here. The current list is available, updated Jan 2013 - here. We are making this available on PCTWeb to show the international uptake and applications of the theory. Or you may like to join the Student PCT Facebook Group by clicking the icon below...

Further Introductory Videos on PCT

In the YouTube video below, Warren Mansell explains the benefits of taking a PCT approach to teaching psychology in this TEDx talk at Burnley College in 2012.


PCT50 Conference, University of Manchester, UK

For the audio & powerpoints of Rick Marken's presentation on research methodology, click here.

Two online videos of Bill Powers' demonstrations:




Getting Started

This site gives you all you need to get your head round PCT – the key idea, its history, and its growing impact on our world view – from work to leisure, the science lab to the classroom, home life to world affairs.

Just click on one of the 10 tabs at the top of the screen to get started!

Or you can try one of the Quick Start links on the right of the page to see the theory in action.


The Evidence Base for PCT & Mental Health Applications

The current evidence base for PCT, accumulated over the last five decades to the present day, is summarised in a downloadable working document that will be updated regularly pending its publication as a review. Feedback is welcome. A working document of published papers on PCT and its application to mental health is also available here.


Latest Test of PCT in Animal Behaviour

Heather Bell and Sergio Pellis from University of Lethbridge, Alberta, Canada have recently published a pivotal research paper on rat protective behaviour. The paper is now available online. They meticulously measured the behaviour that a rat engages in to protect their food from a conspecific. Their findings indicate, consistent with PCT, that this behaviour is the control of a specific perception - the distance away from the conspecific, rather than the product of any complex linear computation that would follow from cognitive theory or behaviourism. They have since replicated their findings in crickets.

Pellis and Bell have also produced a review article pending publication in the journal Developmental Cognitive Neuroscience which concludes that PCT accounts for a diverse range on observations of behaviour across species.