How many ping-pong balls would it take to fill a 747?

June 11, 2014

ping-pongThere has been much in the press recently about weird and wonderful interview questions. The ping-pong ball dilemma being one of the best known. Incidentally if you want to know the answer it’s a remarkable 31 Million. However, if you want to win the gold star you also need to observe that the balls will all have a weight, and if the cabin and hold are filled completely, this will add up to a considerable tonnage. 83 Tonnes! The plane wouldn’t be able to take off. Okay, so now your brain is up to speed, here’s another:

‘You’re on a barge floating in a closed lock in a canal. The barge is full of coal. If you empty all the coal overboard into the water, does the water level on the side of the lock go up or down?’ Hmm.

Good thinkers look past the facts

May 11, 2014

New research shows the best business minds make decisions very differently than we thought. If you want to know more about the inner workings of the executive brain, try this WSJ article.

Soccer brain

June 27, 2012

Swedish researchers have discovered that elite soccer players achieve higher scores on certain tests of cognitive ability than their lower division colleagues, and both sets of players do better than the general public!

Over the moon

It seems it’s all about ‘executive functions’ and working memory. Specifically that successful players are able to constantly assess the situation, compare what’s going on with past experiences, create new possibilities and make quick decisions. In short it’s all about making fast decisions under extreme time pressure. Sounds great! Do the England team know about this?

Sick as a parrot

Of course, there may be a physical explanation. Sports psychologists have known for a while that cognitive abilities are correlated with aerobic capacity. So it may just be that footballers, and other athletes, do better simply because they’re fitter. Mind you, if all this is true, it’s a good argument for getting out there and doing a bit more exercise…

Read the article here.

Let go of the anchor!

January 5, 2012

A thought experiment for you to try:

Below are a set of numbers. Give a friend five seconds to estimate the answer, without resorting to a calculator.

Set-A  8 x 7 x 6 x 5 x 4 x 3 x 2 x 1

Here’s another set of numbers. Find a second friend and give them the same instructions.

Set-B  1 x 2 x 3 x 4 x 5 x 6 x 7 x 8

You will find that the second person gives a smaller estimate than the first, and both will be way off the correct answer (which, rather startlingly, is 40,320).

Maybe you’re not surprised that people find it difficult to quickly multiply eight digits, but why the smaller estimate for Set-B? The answer is provided by the only psychologist to win a Nobel prize, Daniel Kahneman. Check out his ground-breaking 1974 article, written with Amos Tversky, in Science magazine.

A little clue: It’s all to do with ‘anchoring’ – a psychological effect that has a profound effect on our decision-making ability, and which in real life trips us up when we try to buy expensive things like houses or cars!

Photo credit: Scottchan/

Stop being such a cow!

October 14, 2011

Picture the scene: you’re walking down the street trying to decide where to eat. But it’s early evening and all the restaurants are empty. So you pick what you consider to be the most appealing – you think it has the tastiest menu – and go in. After a while some more people come along and see you sitting at a table. They assume that if you’re in there it must be OK, and enter and sit at another table. Very soon there are lots of people in the restaurant and all the other possible eateries are lagging well behind. This process is called the information cascade.

Information cascades are important in economic psychology as they are used to explain the behaviour of financial markets. That’s because they feed the process of speculation, including frantic buying or selling: bubbles v crashes. Now of course all this starts at a vaguely rational level (remember the restaurant example) but rapidly moves into irrational herd-like behaviour. Thus maybe it’s no accident that we talk about confident or ‘bull’ markets! Although perhaps in reality it’s more cow-like: put your head down, eat the grass and stick with the herd.

The bigger point is that information cascades affect all manner of decision-making. And the movement of the ‘herd’ (group, team, board) can be very difficult to resist, even if you, the individual, recognise it as being irrational. People en masse are easily convinced they are moving in the right direction, and frequently do not stop to ask the obvious question: why are we doing this?

At work this is made worse by the fact that many managers do not know how to probe the thinking of their colleagues. They simply base their understanding on what they assume is going on, and assumptions, as we all know, are often vague and unpredictable beasts. The real trick is to return to the beginning and pose clearly framed questions about the logic of projects and plans, and also to ask questions about the organisation. Not just, ‘why are we doing this?’ but ‘why are we doing it this way?’ So maybe the competency lists that are so beloved of HR professionals should always include the ‘ability to ask good ‘why’ questions’ behaviour…


Fairy tales and predicting good leaders

August 8, 2011

“A common phenomenon and problem in leadership practice concerns undue reliance on popular fads without sufficient consideration given to the validity of those ideas…” Click on the link below to read a very good review from Amazure Consulting for the evidence on cognitive tests, personality, situational judgement, emotional intelligence and interviews being ‘effective’ predictors of leadership ability.

Free stuff @

February 12, 2011

Graduates! Just another reminder that there’s a multitude of free psychometric tests and questionnaires on the ‘links’ page of my website at:

Also a growing number of other sites that offer free taster tests, for example you will find verbal, numerical and inductive reasoning tests at:


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