inbeat
Occurring on an inward beat.
[…] two-beat: an outbeat gesture of (usually circumscribed) ecstasis as my glance is released from my bodily self, and an inbeat return of the glance to the bodily-self now modified by having just perceived its own image in the mirror.
Where it comes from
From Middle English inbeten, equivalent to in- + beat.
Adapted from the Wiktionary entry inbeat (CC BY-SA 4.0).