Academic journal article The Psychological Record

Time of Semester as a Factor in Participants' Obedience to Instructions to Perform an Aversive Task

Academic journal article The Psychological Record

Time of Semester as a Factor in Participants' Obedience to Instructions to Perform an Aversive Task

Article excerpt


Participants in psychological research are often recruited from introductory psychology classes that require students to complete a specified number of hours of participation by the semester's end (Miller, 1981; Sears, 1986). Students usually have the option of signing up for studies at any time during the semester, and research over a period of decades has found that students who sign up early tend to differ from students who sign up later in a variety of ways: in gender, with females signing up earlier than males (Harber, Zimbardo, & Boyd, 2003; Richter, Wilson, Milner, & Senter 1981); on questionnaire measures of personality traits (Bender, 2007; Harber et al., 2003; Roman, Moskowitz, Stein, & Eisenberg, 1995; Zelenski, Rusting, & Lars-en, 2003); and in task performance (Casa de Calvo & Reich, 2007; Hom, 1987; Richert & Ward, 1976; Richter et al., 1981).Table 1 summarizes the major differences that have been found between students who choose to participate later versus earlier in an academic term. Given this potential for self-selection bias in a researcher's sample, some researchers have expressed concern that the effects of particular variables could depend on when during a term the participants were recruited (see, e.g., Harber et al., 2003; Roman et al., 1995).

We thank Gitanjali Thiruvadi for her assistance in conducting this experiment.

Correspondence should be addressed to Douglas J. Navarick, Department of Psychology, California State University, Fullerton, CA 92834-6846 (e-mail:

Table 1

Differences in Personality and Task Performance Between Students Who
Sign Up for Studies Later Versus Earlier in an Academic Term

Characteristics of later sign-ups                          References

1. More grade-oriented (early sign-ups more                Bender et
learning-oriented) and have lower academic performance.    al. (2007)

2. More present-oriented (early sign-ups more              Harber et
future-oriented).                                          al. (2003)

3. Lower in personal need for structure; more indifferent  Roman et
or hostile to authority.                                   al. (1995)

4. Higher in sensation-seeking and impulsivity.            Zelenski et
                                                           al. (2003)

Task performance

1. Symbol substitution: Fewer items attempted, more        Richter et
errors.                                                    al. (1981)

2. Digit scanning: Fewer items scanned.                    Richert &

3. Intrinsic motivation: Not reduced by external           Hom (1987)
constraints (reduced in early sign-ups).

4. Anagram task: Less time spent on completing difficult   Casa de
or impossible items (no difference on easy and moderately  Calvo &
difficult items).                                          Reich

5. Simulated interviews: Lower quality questions, biased   Casa de
interpretations of interviewee.                            Calvo &

Harber, Zimbardo, and Boyd (2003) proposed that their construct of time perspective, which is operationally defined by an individual's pattern of scores on the Zimbardo Time Perspective Inventory (Zimbardo & Boyd, 1999), could serve to integrate a variety of dispositional differences between early and later sign-ups. They found that students who participated earlier were predominantly "future-oriented," with a "tendency to relate immediate choices to more distant objectives" (p. 256), whereas those who participated later were predominantly "present-oriented" and were characterized as more focused on immediate concerns, less inclined to pursue goals in an organized manner, and less likely to complete tasks. …

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