Acquiescent responding can distort the factor structure of the BIS/BAS scales

The Reinforcement Sensitivity Theory (RST) is a psychobiological model of personality and psychopathology widely studied in the neuroscience, psychology and psychiatry fields. Despite being the most popular measure of the RST dimensions, the Behavioral Inhibition/Behavioral Activation System (BIS/BAS) scales have a controversial factor structure. In the current study, we investigated acquiescence (i.e., agreement with items disregardful of their content) as a source of bias and distortion of the BIS/BAS factor structure in two independent samples of adults (n = 271, n = 300). As predicted, factors models that controlled for acquiescence yielded better fit to the data, besides a more interpretable pattern of factor loadings and deattenuated factor loadings for negatively-keyed items. Consistent with the original proposition of the BIS/BAS scales, a four correlated factors model was the best representation of the data structure in both samples. In addition, our analyses revealed that the reversed items from the BIS scale only cluster on a different factor from the remaining BIS items because of acquiescence, challenging claims that they measure a putative fear/FFFS factor. We discuss the implications of our findings and the failure to control for acquiescence in studies in the area. •BIS/BAS scales are widely used, but its factor structure is not always replicated.•Acquiescence response bias distorts the factor loadings of BIS/BAS items.•Acquiescence control improves model fit and factor congruence of BIS/BAS scales.•The separation of BIS items into two factors is due to acquiescent responding.