But relax - you can drastically improve your chances with some forward thinking about what employers are looking for. "Interpersonal skills" are the buzz words at the centres, which test candidates' behavioural abilities more than subject knowledge. Firms across the board are looking for "people" people - dextrous in all the arts of communication.
Role plays, group discussions, and personality or "psychometric" tests typically make up the assessment. They can last anything from a day to a week and are often interspersed with more traditional interviews.
What firms are eager for is a certain "lightness of touch", reckons Alyson Burn, director of management consultants ABMD, who are running workshops on assessment centres this summer.
"Employer organisations have realised they can attain much more information on candidates' abilities via an assessment centre. After all, an interview is really just a self report that is not backed up by any evidence of a candidate's ability to perform."
Ms Burn argues that a good candidate might not do themselves justice is if they are not prepared. She said: "Candidates will often be facing the unexpected and this can lead to freezing on the day."
Barry Leskin, Head of Human Resources at Ernst & Young, said they are currently reconsidering their approach to recruitment to focus more on interpersonal skills.
"What we are finding is that some of the people whom we hired 10 or 15 years ago are intellectually bright but that's not enough. That will get us top-notch analysts but it's not all we need to move on in the future. We are after a range of skills, including an inner drive to win, a desire to make things happen and an interest in persuading others.
We have found that introverted people can become successful in some areas but are probably not going to become future partners."
His views chime with those of Ian Du Pre, a partner at Coopers & Lybrand: "We need people with developed interpersonal skills who can mix with clients because we are not a desk-bound organisation.
"What we do is so varied, one day you could be talking to members of a company's board, who might be from an aristocratic background; but the next day, you could be working down a mine.
"One assessment will normally find you out, one way or another. Candidates can't rehearse sitting next to you at dinner."
Socialising with the interviewers and senior members of the firm can be one of the most stressful parts of the assessment experience. Unsurprisingly, it's the gung-ho world of advertising that throws up the worst horror stories.
One female account manager, now at a top London advertising firm, had a "nightmare" interview at Saatchi & Saatchi before landing her current job.
"After an intensive day of assessment, where they had us doing things like building a bridge with paper clips, they took us to an Italian restaurant and plied us with wine.
"Some people had quite a lot to drink because of the stress and nobody felt they could leave until 12.30pm. As we did leave, two personnel people greeted us outside by handing out presentations that had to be prepared for 8.45am the next day. Some people were up all night. That was not nice and I don't know what it proved."
A female colleague's experience is more encouraging: "During dinner at my assessment, I managed to spill a whole bottle of red wine over one of the senior people. I thought that was it, but I still got the job."
Ms Burn advises that candidates should not become hung up on any early mistakes. She said: "It can be particularly upsetting but employers look at the overall performance. People need to rationalise a mistake and realise there will be other opportunities."
But if you are unsuccessful at an assessment centre, it is a good idea to try and find out why, says Alyson Burn: "Firms have something of a moral duty to tell you how you did but if they don't you should ask for feedback."
Ultimately, the trials of the centre will leave you stronger, Ms Burn claims.
"They are a good thing to do. These days, any professional manager or graduate, is very unlikely to get a job or a promotion without going through some kind of assessment."
For information about ABMD's assessment centre workshops, call Alyson Burn on 01753 892494
How To Handle The Pressure
"Remain calm and think about what assessors are looking for," says Ms Burn. "Often they will be rating the ability to handle a difficult situation such as a confrontation. You need to show flexibility. They may have a scenario where you are dealing with a subordinate who has not been up to scratch.
"Rather than start hammering the table and firing them, the assessors will be impressed if you listen and find out the source of the problem. The employee may be dealing with a bereavement or have a genuine difficulty."
Strike a balance between wading in like a tyrant and being a mouse. "It's about getting a middle way," said Ms Burn. "If you dominate group discussions there is a danger you will come across as very domineering.
"You have to tread a fine line of showing yourself to be a good leader but also being very aware of other people's contributions to the group discussion. Let them hold the floor when necessary.
Typically, assessors are turned off by candidates who come across as arrogant or who are not prepared to consider other people's viewpoints, or who have problems asserting themselves."
Praising other people's good ideas will show assessors you are a team player. Resolving disputes between others will also put you in a positive light. Any criticisms you level at other candidates should always be constructive. You may have better knowledge of a topic but resist the temptation to embarrass a fellow candidates.
"The assessors want to see both how well you can express a viewpoint, and how you handle criticism," Ms Burn said. Always try to reach a conclusion even if it is not a unanimous one.
These break down into two types: ability and personality (usually multiple choice) and arguably it is the latter which produces the most anxiety.
"People can feel crushed if they feel they have done badly," says Ms Burn. "At worst there may be a feeling of failure as a person." This feeling is misplaced, she argues.
"You can't prepare for a personality test, I think that would be unethical, and not in the ultimate interests of the person. You have to be genuine, that's why firms do them, because the truth will out. You can't keep up a front for three days.
"A classic question might be to choose what you would prefer to do with your spare time from a list of options such as `go to a party' or `go on a long walk'. This is an over-simplified example but it is used to establish if people are introverts or extroverts."
While firms don't want Coco the Clown, or anyone too brash, broadly speaking they may be more attracted to extroverts for their communication skills and confidence.Reuse content