Researchers condition a flatworm to contract when exposed to light by repeatedly pairing the light with electric shock. the electric shock is a(n)
a. negative reinforcer.
b. conditioned stimulus.
c. conditioned reinforcer.
d. unconditioned stimulus.

Jackie went to the grocery store to pick up yogurt, bread, and apples. first, she picked up a hand basket for carrying her groceries, and then she searched the store. after finding what she needed, she stood in a check-out line. then, the cashier put her items in a plastic bag, and soon after, jackie left the store. as readers of this event, we understand that jackie paid for the groceries, even though it wasn't mentioned, because we are relying on a grocery store