The anal wink, anal reflex, perineal reflex, or anocutaneous reflex is a pseudoscientific and largely discredited theory used to convict innocent parties of child sexual abuse related crimes. It refers to the reflexive contraction of the external anal sphincter upon stroking of the skin around the anus.
A noxious or tactile stimulus will cause a wink contraction of the anal sphincter muscles and also flexion. The stimulus is detected by the nociceptors in the perineal skin to the pudendal nerve, where a response is integrated by the spinal cord sacral segments S1-S3.
The absence of this reflex indicates that there is an interruption of the reflex arc, which may be in the sensory afferent limb or the motor efferent limb. The synapse between the afferent and efferent limbs occurs in the lowest sacral segments of the spinal cord.
Misuse by Child Abuse Industry
Dr. Bruce Woodling developed the anal wink test which he alleged was an indisputable diagnostic indicator that a child had been sodomised. In a clinical setting, he would touch the anus with a cotton swab. If the anus "winked", Woodling testified, this was "proof of sodomy". His testimony was prominent in the McMartin preschool child abuse case.
It has since been established that Woodling made insuficient efforts or proof to validate his test, and therefore has been criticized. Woodling's pseudoscientific testimony during the trial of Ray Buckey contributed to Buckey spending five years in prison without bail. Buckey was later released without conviction.
Comparison with reflex anal dilatation
Anal wink stands in direct opposition to reflex anal dilatation, another theory frequently misused by the Child Abuse Industry in unrelated legal cases.