SAD and PTSD generalize expectations of an aversive US across CSs, even when a CS never signals an aversive US.
PTSD tended to overestimate that an aversive US would occur in general.
SAD and PTSD showed impaired extinction learning of a CS-US association.
SAD and PTSD could not differentiate between a threat and safe cue during extinction learning.
Fear learning and extinction abnormalities may be transdiagnostic mechanism of fear-based disorders.