Complex sentence: Cacioppo and Petty's (1982) need for cognition scale was slightly amended Cacioppo, J.T., Petty, R.E. & Kao, C.F. (1984).
Split into simpler sentences: Cacioppo and Petty (1982) created their own scale to measure the need for cognition. This was subsequently slightly amended Cacioppo, J.T., Petty, R.E. & Kao, C.F. (1984).