FEELTRACE: an instrument for recording perceived emotion in real time

FEELTRACE is an instrument developed to let observers track the emotional content of a stimulus as they perceive it over time, allowing the emotional dynamics of speech episodes to be examined. It is based on activation-evaluation space, a representation derived from psychology. The activation dimension measures how dynamic the emotional state is; the evaluation dimension is a global measure of the positive or negative feeling associated with the state. Research suggests that the space is naturally circular, i.e. states which are at the limit of emotional intensity define a circle, with alert neutrality at the centre. To turn those ideas into a recording tool, the space was represented by a circle on a computer screen, and observers described perceived emotional state by moving a pointer (in the form of a disc) to the appropriate point in the circle, using a mouse. Prototypes were tested, and in the light of results, refinements were made to ensure that outputs were as consistent and meaningful as possible. They include colour coding the pointer in a way that users readily associate with the relevant emotional state; presenting key emotion words as ‘landmarks’ at the strategic points in the space; and developing an induction procedure to introduce observers to the system. An experiment assessed the reliability of the developed system. Stimuli were 16 clips from TV programs, two showing relatively strong emotions in each quadrant of activationevaluation space, each paired with one of the same person in a relatively neural state. 24 raters took part. Differences between clips chosen to contrast were statistically robust. Results were plotted in activation-evaluation space as ellipses, each with its centre at the mean co-ordinates for the clip, and its width proportional to standard deviation across raters. The size of the ellipses meant that about 25 could be fitted into the space, i.e. FEELTRACE has resolving power comparable to an emotion vocabulary of 20 non-overlapping words, with the advantage of allowing intermediate ratings, and above all, the ability to track impressions continuously.