wˌaɪl æt hˈɑːɹvɚd, hiː dɪvˈɛləpt hɪz θˈiəɹi ʌvðɪ ˌɪntəlˈɛktʃuːəl ænd kˈɑːɡnᵻtˌɪv dɪvˈɛləpmənt ʌv kˈɑːlɪdʒˈeɪdʒ stˈuːdənts θɹuː ɐ fˈɪftiːnjˈɪɹ stˈʌdi dˈʊɹɹɪŋ ðə nˈaɪntiːnhˈʌndɹɪd fˈɪfti z ænd nˈaɪntiːnhˈʌndɹɪd sˈɪksti z.
While at Harvard, he developed his theory of the intellectual and cognitive development of college-age students through a 15-year study during the 1950s and 1960s.