__________ is a threat to validity that concerns unintended changes in the equipment or

Which of the following students' statements provides the best summary of the section on visual imagery and interference?

a. Chaim: "Although the early research showed that mental images interfere with perceptual stimuli, the more recent research shows no such evidence." b. Alexei: "Experimenter expectancy plays such an important role that the appropriate research has not yet been conducted." c. Sarah: "Interference is greater if the mental image and the physical stimulus are in the same mode (e.g., both visual) rather than in different modes." d. Rigoberta: "The studies on this topic provide the strongest support of the propositional code that researchers have yet demonstrated."

Which of the following is a secondary punisher?

a. Extreme heat b. Electric shock c. Criticism d. Starvation