Final answer:
The potential ethical concern in Dr. Marcell's memory experiment is deception. In addition, informed consent and debriefing are also important ethical considerations in experiments.
Step-by-step explanation:
The potential ethical concern in Dr. Marcell's memory experiment is deception. Deception involves purposely misleading experiment participants in order to maintain the integrity of the experiment, but not to the point where the deception could be considered harmful. In this case, the participants were not informed about the imagery manipulation prior to participating, which is a form of deception.
In addition to deception, other potential ethical concerns that should be considered in experiments include informed consent and debriefing. Informed consent refers to the participants being fully informed about the nature and purpose of the study, including any potential risks or benefits. Debriefing involves providing complete and honest information to the participants about the purpose of the experiment, how the data will be used, and the reasons why deception was necessary.