Russian experiencer-subject reflexive verbs of emotion vary greatly in the syntactic encoding of their stimuli: poražatʹsja ‘be astonished’ takes the dative case, while obižat’sja ‘feel offended’ takes na ‘on’ + the accusative case, etc. Based on data from the Russian National Corpus, we show that, despite synchronic variegation, many reflexive verbs have been undergoing a unidirectional drift during the last three centuries: the instrumental encoding of the stimulus has gradually been giving way to lexically determined patterns. The use of the instrumental was motivated by its semantic profile: it was closely associated with the meaning of cause. This syntactic change echoes changes in the construal of the stimulus, whereby its cause-like components weaken and its content-like components come to the fore. The evidence in favour of this hypothesis includes the semantic differences between the instrumental case and the relevant encoding devices, a gradual decrease in the proportion of stimuli that are inanimate, the development of emotive meanings on the basis of physical meanings in individual verbs and lexicalization by which reflexive verbs become emancipated from their transitive counterparts. Semantic and syntactic scenarios in the development of reflexive verbs are later partially replicated by corresponding periphrastic participial constructions.