You are doing a study to determine whether smoking nicotine prior to taking a psychology test affects performance on that test. What is the independent variable in your study?

Older children write better than younger children because

a. they have less knowledge about the world. b. they have mastered the mechanical aspects of writing. c. they organize their writing as they retrieve it, often without an obvious structure. d. they don't revise it.

Which of the following is NOT an explanation as to why a newborn's body is not conducive to easy mobility?

a) the baby's head is disproportionately larger than its body b) babies can't get enough nourishment to increase their strength c) the baby's limbs are relatively short in relation to the rest of the body d) babies' bodies are mostly fat, not muscle, so they lack the strength to pick their heads up