I recently came across a great book that teaches children how to count: Father Christmas needs a wee. This is both engaging and educational, and centres around a topic that still intrigues us into adulthood – will the person actually wet himself or herself and if they don’t, how close will they get to this embarrassing social faux pas?
Keeping with this theme, whilst being fun and festive, I’d like to tell two stories of friends of mine that encountered pee problems after Christmas drinks with colleagues and friends. These are true stories but happened many moons ago now. Like how the children’s book teaches us to count, these stories teach us about human error: the important difference between knowledge-based and slip-based errors. For those going out drinking this week these stories should serve as a WARNING, be careful of your intake and also where and when the output may happen!
STORY 1) Rob was heading home from London after a night out drinking with friends – it was an office Christmas party. His colleague, Emma, offered him lift to South East London as she was going home that way anyway, which he gladly accepted. Planning ahead he brought a can of lager with him to drink on the way back. Emma was in the passenger seat, her husband was driving and Rob was in the middle of the back seat with two other women from work either side of him. Not too long into the journey he began to feel the need to wee! It wasn’t that far so surely he’d be able to hold on.
Surprisingly the feeling grew stronger quite quickly. It started to hurt, a pain that only people that have nearly wet themselves know. Beads of sweat started to form on his brow and he fought back to hold the pee in. The others in the car were chatting and laughing, he didn’t want to be a hassle and ask them to pull over, and besides they were on a motorway and so it’d be difficult to do anyway. Weighing everything up Rob thought the best course of action would be just to let a little bit out, which would relieve the pain and buy him time to have a proper wee when he got home. Anyway, you can probably guess the rest… he sat there, looked at his crutch, and watched his plan go increasingly wrong as a dark wet patch grew and grew uncontrollably.
The relief of the abdominal pain paled into insignificance as the gravity of the awkward social situation started to sink in. He was in his colleague’s car, sat next to two other people from work, and without any fuss or whimper he had wet himself. However, and this will surprise you, after such a stupid mistake Rob now performs an amazing act of genius to save the situation – he fakes his elbow being pushed by one of the women and drops his can of drink into his lap. The woman apologises profusely, he accepts it and tells her not to worry. He smiles smugly as he finishes the rest journey not as a perpetrator of a pee crime but rather as the victim of an unfortunate spillage.
What can this teach us about the science behind human error? Well this is a great example of a knowledge-based error. Knowledge-based errors are made because the participant has some incorrect knowledge of the situation. In this case Rob should have known that you can’t just let a little bit out. How could he not know? Surely, everyone knows this fact – if you’re dying for a pee once you pop you ain’t stopping until it’s finished! If Rob had the correct knowledge he would have chosen a different course of action. We see these issues in practice where people make decisions based on incomplete or the wrong knowledge of the situation. We can train people or offer them better support so they have the right knowledge to choose the right courses of action. For example, this article is about a tragic case of a patient not knowing that a hot bath would increase the delivery of drug from a subcutaneous patch – by raising awareness of this danger it’ll hopefully prevent other patients doing the same. This tragic accident might also lead us to review how we communicate this sort of safety critical information to patients, e.g. some airlines have made quite engaging videos to encourage passengers to listen to safety information at the start of their flight.
STORY 2) Stacey was heading back to Charing Cross to go home after drinks with her friends. She started picking up the pace a little as she felt the need to go to the toilet get worse – she now realised that she should have gone at the bar before she left but this was too late now, ‘why the hell didn’t I go at the bar?’ she thought to herself.
Trying to remain composed she broke into a bit of a jog. It wasn’t that unusual for people to be jogging and rushing for a train, and she wasn’t too far from the station now. The fact that she was in a business suit and heels didn’t help. The pain was getting worse but the station was in sight. She was worried. Would she make it?
Whilst still jogging along the pain was getting worse, there wasn’t really a choice of taking it slow, the pee was coming whether she was in the right place or not. She made it into the station but knew that it was going to be close – the pain was now extremely bad. She didn’t want to think about making it just in case this somehow triggered her muscles to relax. She descended the stairs to the ladies’ – was she going to make it? She negotiated the barriers to the toilet – could she hold it for much longer? She made it to a cubicle – it was going to come at any moment! She opened the cubicle door – disaster wasn’t quite there just yet. She got inside – it was so, so, so close. She slammed the door behind her – was she really going to make it?? She pulled down her knickers, she sat on the loo, and relllllaaaaaxxxxxxeeedd… But no! There was fluid flying everywhere! She looked down and saw that in her hastiness she had forgotten to lift the lid off of the loo! The amazing sense of relief was immediately replaced with intense panic as she wet herself – a sensation made so much worse knowing that she still had the rest of the commute home. How was she going to deal with this?
What can this teach us about the science behind human error? Well this is a great example of a slip-based error. Slip-based errors typically occur due to lapses of memory and attention. Here, Stacey forgets to lift the lid of the toilet seat. Everyday slip-based errors also include dipping your paintbrush into your tea rather than your paint pot, leaving your car lights on so you get a flat battery, and pouring orange juice into your cereal rather than a bowl (these examples are taken from Errordiary).
These lapses of memory and attention also happen in more serious circumstances, but unlike knowledge-based errors they do not occur because the person has incorrect knowledge of the situation. We can reduce the risk of these errors by creating resilience strategies and designing situations so they are less likely to occur in the first place (short YouTube clip). For example, some infusion pumps are now used with smart drug libraries so if some data input is grossly outside an expected range, perhaps because the nurse makes a slip-based error, it will alert the nurse e.g. 1000ml was entered instead of 100ml. Mechanisms are also integrated into infusion pumps to reduce the likelihood of a free flow incident, i.e. where the bag empties unhindered into the patient because there is nothing to stop it. Here clips, procedures and alerts help control the flow of fluid throughout the treatment. But we do not always get it right. If we think of the subcutaneous patch we referred to early it is entirely plausible that a patient could have a hot bath and forget that they shouldn’t. Here they have the right knowledge but they have a slip of memory or attention. Part of the advantage of subcutaneous patches is that they can be implanted then almost forgotten about. This is a blessing and a curse in this situation. What interventions could we make to help here?
Poo stories have been used to demonstrate the importance of psychology and interaction design in the prevention of error (see this Bright Club Comedy Set). This article breaks new ground by showing how wee stories can teach us the difference between knowledge-based and slip-based errors. Like the children’s book, Father Christmas needs a wee, or even the mole that knew it was none of his business these topics seem to intrigue us – perhaps because of their taboo nature – and used in the rigt way we can learn a bit more about the world we live in too.
- Knowledge-based errors are made because the person doesn’t have all the facts, or has some of the wrong facts, so they choose the wrong action.
- Slip-based errors involve lapses of memory and attention.
- Be careful how much you drink.
- Human error can be amusing and fatal, we can reduce the risk of accidents if we understand what has happened properly (see CHI+MED for more on patient safety).