Which trait is a primary focus of Hans Eysenck's research on personality?

Ache infants tend to walk later than Jamaican and Kipsigis infants. This is due in part to

a. genes. c. parental expectations. b. delayed gross motor development. d. delayed fine motor development.

Two groups of rats have a small pellet implanted under the skin. In Group A rats the pellet contains morphine, which is slowly absorbed over a 72 hour period

In Group B rats the pellet contains an inert substance. The rats are kept in their home cages for the three days after the pellet implantation. Both groups are then tested for analgesia by being injected intraperitoneally with a small dose of morphine. This test consists of the rats being placed on a hot surface and they are timed to see how long it takes them to lick their paws. (It is assumed that the longer it takes the rats to lick their paws, the more the analgesia.) Group A rats display much less of an analgesic response than Group B rats. Is this tolerance phenomenon more compatible with a pharmacodynamic or a context specific mechanism for tolerance development? Explain your reasoning. What will be an ideal response?