Measuring Implicit Motives with the Picture Story Exercise (PSE): Databases of Expert-Coded German Stories, Pictures, and Updated Picture Norms.

We present two openly accessible databases related to the assessment of implicit motives using Picture Story Exercises (PSEs): (a) A database of 183,415 German sentences, nested in 26,389 stories provided by 4,570 participants, which have been coded by experts using Winter's coding system for the implicit affiliation/intimacy, achievement, and power motives, and (b) a database of 54 classic and new pictures which have been used as PSE stimuli. Updated picture norms are provided which can be used to select appropriate pictures for PSE applications. Based on an analysis of the relations between raw motive scores, word count, and sentence count, we give recommendations on how to control motive scores for story length, and validate the recommendation with a meta-analysis on gender differences in the implicit affiliation motive that replicates existing findings. We discuss to what extent the guiding principles of the story length correction can be generalized to other content coding systems for narrative material. Several potential applications of the databases are discussed, including (un)supervised machine learning of text content, psychometrics, and better reproducibility of PSE research.

Predicting affective appraisals from facial expressions and physiology using machine learning.

The present study explored the interrelations between a broad set of appraisal ratings and five physiological signals, including facial EMG, electrodermal activity, and heart rate variability, that were assessed in 157 participants watching 10 emotionally charged videos. A total of 134 features were extracted from the physiological data, and a benchmark comparing different kinds of machine learning algorithms was conducted to test how well the appraisal dimensions can be predicted from these features. For 13 out of 21 appraisals, a robust positive R2 was attained, indicating that the dimensions are actually related to the considered physiological channels. The highest R2 (.407) was reached for the appraisal dimension intrinsic pleasantness. Moreover, the comparison of linear and nonlinear algorithms and the inspection of the links between the appraisals and single physiological features using accumulated local effects plots indicates that the relationship between physiology and appraisals is nonlinear. By constructing different importance measures for the assessed physiological channels, we showed that for the 13 predictable appraisals, the five channels explained different amounts of variance and that only a few blocks incrementally explained variance beyond the other physiological channels.