'It's not size per se - it's the contrast ...'

Matthew Brace asks male observers to explain an age-old question of attraction

Dr Simon Bearder, primatologist from Oxford Brookes University: This is very deep. There has been recent research into this by psychologists looking at certain types of sexual behaviour. A predominant attraction in males is the rear of the female and that can be mimicked by the bosom. But it's not size per se, it's the contrast provided that attracts men. If a woman is very skinny, she doesn't need to have big breasts to attract a man - they can be quite small but the contrast is greater. It's not just breasts, there are many other things that attract a man to a woman. When it comes to advertising, a picture of a woman with obvious breasts - that high contrast - can't fail to grab men's attention.

Wesley Benton, pilot: If I stand in front of the mirror naked, I think "Eugh, that's not very attractive", but women's bodies are lovely. A major part of that difference is their breasts. I used to love big breasts, I was obsessed with them, but now I think I'm changing. My current girlfriend has no breasts whatsoever, but it doesn't bother me.

George Andersen, unemployed: If you look at the likes of Demi Moore and Pamela Anderson Lee, they look unnatural. They defy gravity almost. That's too over-the-top for me. A lot of men do go for bigger breasts - it's a macho, laddish thing. But I think on the quiet they might prefer smaller ones. It's all about proportions.

Bob Trant, mini-cab controller: I can't help noticing a woman with a big pair of breasts if she's walking in the street. But it can be a hassle if you are going out with a woman and all the other blokes are staring at her front. Big breasts will probably always sell things because it grabs your attention - only the attention of the blokes, though.

Justin Greetham, photographic special effects expert: I must admit I do like a big pair of breasts, they are more comfortable - there's probably a link with childhood. But I don't know if it is a key feature behind a relationship.

Simon McQueen, art director: In the case of bra adverts, the image has to sell the product, show what it does and what it looks like. I don't think the women on the bikini adverts at the moment wearing the bikinis are top-heavy. They're sort of average. A lot of men might think big is better, but there's big and there's ridiculous.

Paul Temple, postgraduate student: Big breasts? Absolutely. Can't beat them. Some people say that it's personality that counts, but not for me. I think men in general definitely favour big breasts. Without a doubt.