FMR1 and fragile X syndrome: Because Fmr1−/− mice exhibit SOR (Chen and Toth, 2001; Rotschafer and Razak, 2013, 2014; He et al., 2017), just like people with FXS, we hypothesized that they would be unable to tune out sensory distractors, and this would have a negative impact on their performance on the visual task.