The fact that the scandal of MPs’ expenses rumbles on for a third week is testament to just how outraged the general public are about the revelations coming out of Westminster. Although the stereotype of politicians is not always one of utmost honesty and integrity, exploring the explanations for MPs’ behaviour from a psychological perspective is not only fascinating but, perhaps more disturbingly, it leads us to the question – when we look closely - would we, the ‘morally outraged general public,’ really behave that differently?

According to equity theory, in a working environment, we seek to maintain equity between what we put into work and the outcomes we receive for it. For many, a large part of the outcome is salary. So for MPs, in terms of outcomes, their average salary, as of April 2009, is £64,7661. In terms of input, the role requires long hours, many away from home. There is also some longer term risk involved as MPs aren’t in a position to pursue a career away from politics, in preparation for the day their political star begins to wane.

Back to the theory, if we feel there is imbalance between input and outputs – i.e. if we’re getting out less than we’re putting in – we need to address this and rebalance the psychological score card. For those MPs who feel they are underpaid, adding an extra £24,000 to their salary can go a long way to addressing the balance! If the mentality is ‘it’s a part of the salary that I’m entitled to’ rather than ‘it’s a fund which I can draw on, if necessary, to ensure I’m not out of pocket for doing my job’ - it then becomes fairly irrelevant what the money is actually spent on – and certainly we’ve seen some of this from some of the expense MPs thought would never see the light of day!

Although MPs have had much more latitude here (that’s what happens when you make your own rules!) I would suggest that this psychological ‘equaling things up’ is something we all do. For most of us, it’s just that our options are much more limited. In organisations, some people reduce their productivity – either not engaging in discretionary behaviors, such as staying late or helping out a colleague - others may simply slide into underperformance; a small minority may equal things up by increasing their package through stealing, for example, office supplies (a recent survey reported that toilet roll is the most frequently stolen item from businesses). Have you ever slacked off a little and justified it because you’ve worked really hard previously? Have you ever ‘borrowed’ some post its and used them at home; thinking its not an issue as you’ve more than made up for it in the unpaid overtime you’ve done? The principle is the same!

Before you stop reading this and shoot me down in flames, I’m neither defending MPs’ behaviour nor suggesting the British public is morally corrupt. However, this could help to explain why so many MPs have put so much effort into working the rules to ensure they claim as much as they can.

For me, a particularly shocking element of this story is the prevalence across Westminster; it feels like most of the MPs are at it in some form or other, regardless of political affiliation. To help explain this, we can again look to psychological theory. The premise of social proof theory is that we look to others about how to behave, especially in situations where we are unsure. So, for MPs whose moral conscience may have got the better of them about a particular claim, they only have to look at their peer group to see that dubious claims are just part of the social norm. Again, we all do this, it’s part of the human condition – have you ever glanced across the dinner table to double check you’re using the correct piece of cutlery or, in a foreign country, looked around for clues about how to order a meal or use public transport? We all look to others to check what’s normal when we’re unsure. Don’t underestimate this phenomenon, it is a powerful one. In one famous psychological experiment, most people ignored smoke coming from beneath a door when everyone else did the same. Where people were on their own, they quickly raised the alarm. We’ll put our safety at risk before we break away from the ‘norm’.

It’s all very well to explain this behaviour, but it doesn’t make it right. It may, however, help to inform how we can prevent things like this happening again. Making the rules tighter and more explicit will go some way to making the norm for expense claims more appropriate and realistic; employing an independent body to ensure this is enforced will support this process as well. The fury of the public and the openness of the Freedom of Information Act should also help harness the power of social approval, which is a part of human behaviour that all MPs should understand!

However, the really thorny issue is around equity i.e. MPs getting out what they put in. Pay is central to this - should we really even consider increasing pay? Should we encourage the ‘professional politician?’ Intellectually, the argument is yes, we should certainly consider it. If, as a group, MPs truly feel that the rewards they receive from their role are not equal to the effort they put in, the risk is that they will simply find other ways to equal things up – and the problem just moves elsewhere; it may be less obvious but it will still be there.

In these uncertain times, for MPs (and for the rest of us for that matter) – the value of actually having a job – even one that doesn’t give us quite what we deserve - may temporarily readdress the balance to some extent. Combined with tighter rules, this could bring MPs into line for a while, but without addressing some of the fundamentals of equity of effort and outcome, the question is not whether this is just a sticking plaster, but how long before the sticking plaster peels off?