We compare the behavior of a small truncated coupled:map lattice with rando
m inputs at the boundaries with that of a large deterministic lattice essen
tially, at the thermodynamic limit. We find exponential convergence for the
probability density, predictability, power spectrum, and two-point correla
tion with increasing truncated lattice size. This suggests that spatiotempo
ral embedding techniques using local observations cannot detect the presenc
e of spatial extent in such systems and hence they may equally well be mode
led by a local low:dimensional stochastically driven system.