Affinity 2.5

Affinity 2.5 is a computer based ipsative (“forced-choice”) assessment of sexual interest.  It combines two overt measures of sexual interest (designed to enable the subject to report the age and gender of sexual preferences in some detail) with a covert, ‘viewing time measure’ (VTM).  The VTM is based upon the well-established finding that individuals spend longer time gazing at images they find sexually attractive.  It was established using the Affinity 1.0 prototype that these images did not need to be sexually explicit or arousing in any way.  It was also established that this phenomenon persisted (perhaps was even potentiated) when the subject was actively engaged in rating the sexual interest of images.  The delay time for a rating can thus be used as a validity measure of the rating itself.

The ipsative (“forced-choice”) construction of the Affinity 2.5 is an important feature.  This is a specific type of measure in which respondents compare two or more desirable options and pick the one that is most preferred (sometimes called a “forced-choice” scale).  This is contrasted with measures that use Likert-type scales, in which respondents choose the score (e.g. 1 to 5) which best represents the degree to which they agree with a given statement.  While mean scores from Likert-type scales can be compared across individuals, scores from an ipsative measure cannot. A strength of ipsative measures is that it is generally more useful for evaluating traits within an individual, whereas Likert-type scales are more useful for evaluating traits across individuals.  Additionally, ipsative measures can be useful in identifying faking.