A team of sociologists is commissioned to study the effects of lighting levels and amount of time for breaks on workers' productivity in an office setting. Before the study begins, office workers are told why the researchers are there. When the team analyzes their data, they find that no matter what they do, productivity levels go up while they are physically present. When the team is not physically present, productivity levels return to normal. What is the likely explanation for these findings? excessive objectivity the Hawthorne effect a lack of confidentiality a lack of a control group