When a particle tunnels through a barrier it interacts with that barrier for a time that has been analysed by the authors. An appreciable number of other investigators have, with modest variations, come to the same result. Collins, Lowe and Barker (1987) have criticised this approach and advocated an older answer which depends primarily on the phase changes encountered at the turning points of the barrier, and not on barrier thickness, nor on the exact potential variation within the barrier. This is a rebuttal of their criticism. © 1988 IOP Publishing Ltd.