Heather M. Caspers University of Northern Iowa

 Methods and materials of study must approximate the real-life situation that is being examined  Connection between ecological validity, external validity, and generalizability  External validity: results of a study can be generalized  Independent of each other

 This issue has been debated by a variety of experts  Buckout and Loftus: usefulness of experimental findings  McCloskey et al. and Konecni and Ebbesen: raised the issue of ecological validity

 Yuille and Wells (1991)  Ecological validity is not a feature of the design itself  Caution should be used in generalizing from controlled research studies to real-world contexts  Experts should present all information, even limitations

 Is eyewitness identification context dependent? (Yuille, 1993)  Generalizations must be sensitive to contextual effects  More methods of research (field studies may be more difficult, i.e. time, money, cooperation)  Call for caution until appropriate research is completed  Combination of controlled, archival, and field research

 How comparable is a staged event to actual criminal event?  Laboratory witnesses vs. witnesses of criminal events

 Cutshall and Yuille’s studies  Examined a variety of different actual crimes in conjunction with police department  Found different results  Hard to mislead witnesses  Stress may not necessarily impair witnesses  Accuracy only delays slightly over a longer period of time

 Penrod and Bornstein examined effects of a variety of different variables to assess generalizability  Concerns about ecological validity are not founded  May actually be underestimating effects

 Frye test  Expert must be qualified to testify about the subject matter  Expert must testify about a proper subject  Testimony must conform to a generally accepted explanatory theory  Probative value of the testimony must outweigh its prejudicial effect

 Yuille and Pachella express concerns about eyewitness experts testifying about these issues  Jurors do not need to be told about the relative performance of participants in the laboratory  Larger issue relates to experts testifying in trials  Juror knowledge  Influence on jurors

 Mock trials (Bornstein, 1999)  Opposing eyewitnesses  Devenport and Cutler, 2004  Jurors found the defense-only expert less credible when there was an opposing witness that brought up issues regarding ecological validity

 Be aware of ecological validity concerns  Conduct research outside of the laboratory if possible  Replication