Galaxy Classification: Citizen Scientists versus Experts

We present the differences of morphological galaxy classification between non-experts and experts. The non-experts are represented by college students and a retired adult community, who use an online application to visually classify galaxies selected from a galaxy morphology catalog. We find that the non-expert group lags the expert classification by one Hubble type behind, for instance, the non-experts classify a set of galaxies with Sb, while the experts classify the same set as Sc. We believe the reason is because the Hubble sequence is increasing the asymmetric structures towards later types. Our results show that the experts have the ability to identify more detailed structures, which the laymen commonly do not recognize.