In survey research, acquiescence response style/set (ARS) and extreme response style/set (ERS) may distort the measurement of attitudes. How response bias is evoked is still subject of research. A key question is whether it may be evoked by external factors (e.g. test conditions or fatigue) or whether it could be the result of internal factors (e.g. personality or social characteristics). In the first part of this study we explore whether scale length—the manipulated test condition—influences the occurrence of ERS and/or ARS, by varying scale length from 5 till 11 categories. In pursuit of this we apply a latent class factor model that allows for diagnosing and correcting for ERS and ARS simultaneously. Results show that ERS occurs regardless of scale length. Furthermore, we find only weak evidence of ARS. In a second step we check whether ERS might reflect an internal personal style by (a) linking it to external measures of ERS, and by (b) correlating it with a personality profile and socio-demographic characteristics. Results show that ERS is reasonably stable over questionnaires and that it is associated with the selected personality profile and age.