They normally comprise aptitude and personality tests, so you get a series of numerical and verbal understanding tests, then a couple of personality tests which I guess are ultimately based on Myers-Briggs or something similar.
Numerical tests are pretty straightforward - they require you to answer questions based on tables of figures etc.
Verbal tests are normally based on a paragraph of text like:
“Many organisations find it beneficial to employ students over the summer. Permanent staff often wish to take their own holidays over this period. Furthermore, it is not uncommon for companies to experience peak workloads in the summer and so require extra staff. Summer employment also attracts students who may return as well qualified recruits to an organisation when they have completed their education. Ensuring that the students learn as much as possible about the organisation encourages interest in working on a permanent basis. Organisations pay students on a fixed rate without the usual entitlement to paid holidays or sick leave.”
And then a series of statements which you have to decide if they are true, false or it is impossible to say based only
on the paragraph above:
Statement 1 - It is possible that permanent staff who are on holiday can have their work carried out by students.
Statement 2 – Students in summer employment are given the same paid holiday benefit as permanent staff.
Statement 3 – Students are subject to the organisation’s standard disciplinary and grievance procedures.
Personality tests list statements you have to agree/disagree with on a scale of 1-5, or you have four statements and have to say which one is most like you and which is least like you... The tricky thing is that normally you look at the statements and they are either all like you or none of them are like you - or they imply a negative trait but you still have to say one of them is like you.
I enjoy meeting new people: Agree completely, Agree slightly, Neither agree nor disagree, Disagree slightly etc
I like helping people
I sometimes make mistakes
The motivation tests are roughly the same, but deal with motivation: i.e. Haveing a new member of staff to train motivates me: alot, slightly, not at all etc
The most important thing about the tests is they produce numerical data, which one of Satan's minions will crunch and then put a tick or a cross by your name depending on whether you fit in the right box. I decided a few years back that I would simply never work for a company who thought that psychometric testing was a good way of evaluating people - what does that say about my personality??
Loads of info on these tests on graduate websites like Prospects
and on http://www.shldirect.com/
(The examples above come from the second link).