Intrusion, the second main type of interaction, has comparatively few distinct varieties. The chief reason for this would seem to be that for once considerations of word order or structuring hardly arise. Another contributory factor is that in general the distinctions between the different forms of imagery have little practical relevance here. In particular, the distinction between implicit imagery (i.e. metaphor) and explicit (e.g. simile) is not of much consequence in most cases – with one exception. The exceptional case has already been treated, albeit briefly. In its most rudimentary form, intrusion is confined to comparison and short simile, where a predictable ’N as V’ (or ’more N than V’) is replaced by ’T as V’ (’more T than V’).