FACES: Schematic Faces Test

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Signal detection application for images of schematic faces.

 

This task uses images such as those used by Öhman, Lundqvist & Esteves (2001) in research (see upper figures). A large number of test institutes offers many possibilities for experimental research. Standard (as used by us) there are after each practice block 2 subtasks (blocks) with 50 trials each. In each trial a matrix with 9 schematic faces is shown very briefly, where the task is to indicate whether there is a different face or not. In half of the number of trials there is a different face, in the other half all 9 faces are identical. In one of the blocks the different face is an angry face amid of neutral faces, in the other block it is a happy face in the middle of neutral. The faces are presented upright, but it is possible to show the faces upside down. The presentations are very short (50 ms), and backward masking is applied by presenting a random pattern of lines over the faces for 200 ms. The faces are shifted slightly vertically, to make recognition on the basis of “line detection” more difficult.

The task can also be performed with further abstracted “shields” involving symmetry in the vertical plane (figures below).

The RT is registered on every trial as well as the accuracy. Based on the percentage of hits and false alarms, the results are processed with the signal detection method, leading to a d` (d-prime) and a ß (beta). The d` is a measure of the sensitivity and sharpness of the perception (the higher the more sensitive the perception), the ß is a measure of the response bias (the lower the more the subject is inclined to decide in case of doubt that a different face – “signal” – has been presented).

This task is mainly about the distinction in perception of angry and happy faces. The rationale behind the composition and application of this task is the idea that angry faces are detected faster and better than happy ones (a position that can be defended from an evolutionary point of view). This distinction is clearly evident from the data. The possible setting of faces turned 180˚ is to show that the angry-happy effect is not only based on a difference in physical configuration, but indeed on the basis of emotion.

An English language version is available.

Normative data, based on the d` and ß measures, have been collected among students (faces version: N = 1103, shield version: N = 588).

Literature:

Öhman, A., Lundqvist, D. & Esteves, F. (200). The face in the crowd revisited: A threat advantage with schematic stimuli. Journal of Personality & Social Psychology, 80, 381396.

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