Classical conditioning is only effective in humans when they are infants

According to Ohlsson's representational change theory, which of the following is not a way in which one can change problem representation:

a) Constraint relaxation b) Re-encoding c) Elaboration d) Incubation

Researcher George Vaillant combined samples from three studies: male Harvard graduates, boys from low-income urban families, and women with high IQs

Each of the studies began in the early decades of the 20th century and followed their samples with assessments every year or two from childhood or emerging adulthood into late adulthood. Vaillant conducted which of the following research designs? a. a longitudinal study b. a cross-sectional study c. a quasi-experiment d. a case study