After Gibson and Walk's original studies, researchers now believe that depth perception exists as early as

Which learning disability is characterized by difficulty in making arithmetical calculations?

a. analytical dysfunction b. dyslexia c. dyscalculia d. dysnumeracy

Sickle cell disease is caused by a genetic mutation and, when untreated, results in disability and early death. However, the mutation that causes sickle cell disease is associated with protection against malaria, especially early in life. As a result, you would expect to see sickle cell disease ____

a. eradicated as quickly as malaria is eradicated b. occur predominantly in populations that have historically low rates of malaria and similar diseases c. occur at similar rates in all populations, since malaria can be found anywhere mosquitoes, which transmit malaria, are found d. occur at higher rates among populations whose genetic heritage can be traces to areas with a high incidence of malaria