Category Archives: Biological psychology

Mind like a sieve

Mind like a sieve?(Many thanks to Eleanor Rule for the drawing)

Mind like a sieve?
(Many thanks to Eleanor Rule for the drawing)

You’ve got a ‘mind like a sieve’ is a common way of telling someone that things just fall through their heads and that they can’t remember anything. However sieves can retain some of the stuff that is being filtered through them. Is it that we filter out the ‘larger’ bits of information and allow the ‘smaller’ bits of information to fall through our minds?

Even people with awful memories do still remember some things. Maybe we all differ in the size of the holes in our sieve-like-minds. To a certain extent, whether we remember something depends on if we have paid any attention to it. If you are not aware of something, how could you remember it? There are many theories on attention, one particularly relevant one to this idiom is Donald Broadbent’s. He developed the filter model of attention which claimed that our selective attention occurs before any processing of the information due to our limited cognitive capacity. In other words, Broadbent was suggesting that our attention, and in turn our memory, works like a sieve, filtering out the unnecessary information in the early stages of processing leaving just the relevant stimuli to be processed to a higher level. These stimuli could be something you’ve heard or seen or anything that you are trying to remember. This is an early selection view of attention and is where there is a selective filter based on the physical properties of the stimulus before any higher level processing occurs.

However, there are some phenomena which can’t be explained by an early selection view of attention. For example, Colin Cherry coined the term ‘the cocktail party effect’ which many of us have experienced. Imagine you are at a party where there are lots of people and lots of conversations going on at the same time. It is possible to focus on a single conversation in a noisy room though also you can pick out words of importance from an unattended conversation such as your name. This implies that we don’t select what to pay attention to before any higher level processing occurs meaning that Broadbent cannot be completely correct with his filter theory of attention.

This might mean that our encoding of memories after the higher level processing of the stimuli is what acts as a sieve. The salience of the information plays an important role in whether something is encoded into our long term memory. Perhaps it is in recalling our memories that we filter out unimportant information. There is a trade-off between accuracy and actually remembering things. For every time we recall a memory we bring it into a labile state, a state where the memory can be easily altered as we think about it. But if we didn’t recall these memories we would forget them altogether.

There appears to be some truth to the saying ‘mind like a sieve’ though this act of filtering out unimportant information seems to occur at multiple stages of the processing of the stimuli. In some ways then we all have memories like sieves! This sounds like a bit of an ineffective system for remembering things. Though if you think of the fact that we have limited cognitive space for memories then it makes sense to filter out the unimportant things. If we didn’t, we wouldn’t be able to remember the important things that we really shouldn’t forget!

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Old habits die hard

Even a power cut doesn't stop Tim from watching TV...

Even a power cut doesn’t stop Tim from watching TV…

The phrase ‘old habits die hard’ is often used to excuse some behaviour that people wish they could stop. Though is there any truth behind this common phrase? I will discuss whether it is possible to break our old habits or whether they do indeed die hard.

When talking about habits, or habitual behaviour, I am referring to behaviours that are insensitive to reinforcer devaluation. By this I mean that an action, such as pressing a lever to gain a reward, continues even if the reward is no longer present or of value.

Many of our actions in typical daily life consist of habits such as washing our hands after going to the toilet. A lot of these behaviours are ‘neutral’ though they can be positive or negative actions. The phrase ‘old habits die hard’ is often used in conjunction with negative behaviours that can be detrimental to the individual or just no longer necessary. For example, smoking or biting their nails and laying the table for someone who has recently moved out, respectively.

Another type of behaviour that occurs on a frequent basis is goal-directed behaviour which is a behaviour where you have the representation of the final output in mind, i.e. you’re performing a particular action to achieve a certain goal. Goal-directed behaviours can evolve into habitual behaviours and this difference between habitual and goal-directed behaviours is represented by a change in the circuitry of the striatum, a part of the forebrain.

The question of whether old habits die hard is really a question of how difficult it is to break your habits, if even possible. To know if it is possible to break a habit it would help to know how the habit was formed in the first place. As behaviour moves from goal-directed to habitual there is an equivalent shift from the ventral (goal-directed) to the dorsal (habitual) part of the striatum. There are many studies that have demonstrated these functional differences between different regions of the striatum.

In terms of brain connectivity, to break an old habit, the brain connections should be from the ventral striatum as opposed to the dorsal striatum. Though how is it possible to do this? There is a wealth of research on the formation and maintenance of habits though I have not found any papers that have studied, in depth, the breaking of habits. There are papers however which suggest that it is not an irreversible single path leading from goal-directed to the habitual circuit but rather that there is ongoing competition between the two circuits. The behaviour is then controlled by which ever circuit is stronger at that time. So perhaps when people say that old habits die hard it means that their behaviour is controlled by their dorsal striatum and therefore their habitual brain circuit.

This idea of competing circuitry does suggest that it is possible to break old habits and return the behaviour to a goal-directed response. The competition between circuits is adaptive in most situations as the behaviours can be altered under changing situations. These changes in behaviour though are probably slower than if the habit circuit had never developed dominance over the goal-directed circuit. But there is a huge advantage to us that we can develop habitual behaviours which are automatic and therefore do not take up our limited cognitive power.

The competition between the two circuits could also explain the individual differences between how easy different people find it to kick a habit. You probably know someone who tries to give up smoking every month and maybe also someone who just decided one day that they would stop and haven’t smoked since. It may be that these individual differences in the ease with which people can give up habits is due to a difference in the dominance of the different circuits and therefore the ease with which someone can change their behaviour back from habitual to goal-directed. In conclusion, it seems that the phrase ‘old habits die hard’ is an over simplification of the difficulty some people find in changing their habitual behaviour back to the voluntary, goal-directed behaviour controlled by their ventral striatum.

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