The tendency for optimal levels of performance to be associated with moderate levels of arousal is known as

As development progresses, the neural plate starts to form a groove, which by embryonic day ______ fuses to form the _________________

a) neural shaft b) neural ectoderm c) neural tube d) neural tunnel

Ruling out alternative theoretical explanations of results is the concern of ______ validity

a. internal b. construct c. external d. statistical