A psychologist shows participants films designed to make them either happy or sad. She measures the participants' brain activity levels with an electroencephalograph (EEG) during the films. This psychologist probably is conducting research on:

The map above shows the expansion of the greek empire. which statement best describes the greeks during the 4th century bc? a. greek expansion was stopped by the persian empire. b. the greek empire controlled parts of africa, europe, and asia. c. the greeks were threatened by barbarian tribes in europe. d. greece did not have friendly relations with ancient egypt.