sˈɪns hɪz wˈɜːk, fˈɜːðɚ ɹᵻsˈɜːtʃ ˌɔn ᵻpˌɪstɪməlˈɑːdʒɪkəl bᵻlˈiːfs ænd ɹˈiːzənɪŋ hɐz ɹᵻfˈaɪnd, ɛkstˈɛndᵻd ænd ɐdˈæptᵻd pˈɛɹiz dɪvˈɛləpmˈɛntəl sˈiːkwəns.
Since his work, further research on epistemological beliefs and reasoning has refined, extended and adapted Perry's developmental sequence.