Even pushing one has caused serious problem. In Australia one A320 or 319 when descending to 3000ft from 7000ft passing 5000ft they were cleared for approach. Pilot stabbed EXPED instead of APP then trying to press EXPED again to cancel it (that doesn't cancel EXPED) this time he stabbed ATHR causing THR LK which he disconnected using ID button which increased thrust to climb, then he disconnected AP causing 38kt flap overspeed. Pressing any switch is see, identify and do action. Any memory Muscle or otherwise or habit should play no part in it. Incidentally both PF and PNF were check pilots.