Dr Anne Moffatt is a computer expert and in the 90s her company was commissioned by Australia's largest poker machine maker to program their machines, as they were rolled out across the country.

“One of the programmers who was actually writing the code said to me, 'I don't like this, I just don't feel right about what I'm doing'," Anne said.

Anne says the programming predetermined how much and how often you win or lose, employing tactics to keep you playing longer.

“He said did you know they've got ten full time psychologists on their books to help people continue betting more than they'd want and I said, 'Come on, that is just a rumour',"Anne said.

But Anne is confident it wasn't. She says the company is still around and is “one of the major players in the poker machine market”.

Anne says that company was Aristocrat: business that has just announced a $34.7 million dollar half-yearly profit.

Aristocrat denies they employ psychologists and so did Ross Ferrar from the Gaming Technology Association in a Senate hearing in May this year.

But Dr Moffatt is undeterred.

“You can make the machine look as if it has nearly won, you can show an icon peeping down at the corner of the machine as if, 'Oh, I was only one icon off on a particular line, I would have won, I would have won a lot of money'," Anne said.

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Dr Charles Livingstone is Australia's leading poker machine researcher. He says the psychological principals of reinforcement introduced in the 1990's remain today.

“The machines are wired, they have perfect data, they know what works, they know what doesn't work and the people playing them are providing them with that information," Dr Livingstone said.

“There is an enormous amount spent just on developing games. I mean this is serious amounts of money which is going into making machines - building a better mouse trap if you like,"Dr Livingstone said.

Dr Livingstone says companies have instant access to data to tell what style machines are popular and which are not.

“Something like 60 per cent of the money going through the poker machines in Australia is coming out of the pockets of someone with a gambling problem."

“There are two basic psychological principles in operation on a poker machine, both of them are about reinforcement. One of them is called 'operant conditioning' and that is the pattern of wins - if you have an irregular pattern of wins on a machine it is much more likely to get people to keep playing it than if you have predictable pattern," Dr Livingstone said.

The other is known as 'random reinforcement'.

“So if you know the machine is eventually going to pay out but you don't know when, it is much more likely that you will want to keep playing it and you become conditioned to get those little wins over again," Dr Livingstone said.

The growing number of people conditioned to losing money is prompting calls from a peak lobby group for maximum bets to be limited to one dollar.

Contact information

If you feel that gambling is becoming a problem for you or someone you know, there are government-run hotlines in every State.

Find out more at www.gamblinghelponline.org.au or find an agency near you for free counselling and support here.

To speak to or find a face-to-face counsellor phone the helpline on 1800 858 858.