We analyze the dynamic behavior of coupled oscillators with time-delay
ed interaction under a pinning force. With intermediate delay times th
e system shows multistability of synchronized and desynchronized state
s. In the synchronized states there are multiple states with different
collective frequencies showing hysteresis as the pinning force increa
ses and decreases. In the desynchronized states the oscillators are di
stributed almost uniformly. The multistability presents a possible mec
hanism of the perception of ambiguous or reversible figures.