Skip to main content Skip to main navigation Skip to footer content


Ryan Ditchfield, Ph.D.

Assistant Professor

Office Phone Email
S2 149 559.278.2812

Biographical Sketch

Navigating the criminal justice system requires people to make difficult decisions. Eyewitnesses must decide whether a presented suspect is the perpetrator or not, risk assessors must decide whether to release offenders from prison or not, suspects must decide how to respond in police interviews, and police officers must decide how to interact with eyewitnesses, suspects, and other actors in the justice system. When these decisions are wrong, there can be serious consequences: misidentifications, wrongful convictions, and loss of public trust in the justice system.  

As a legal psychologist and Assistant Professor in the Department of Criminology at Fresno State, Dr. Ditchfield investigates how individuals in the criminal justice system (e.g., risk assessors, eyewitnesses, criminal suspects, and police officers) make hard choices in high-stakes situations where those choices appear to have real consequences. By investigating decision making via experimental and modern statistical techniques, Dr. Ditchfield’s work provides insight into the psychological mechanisms that cause legal decision-making errors.  

Dr. Ditchfield graduated from Fresno State in 2016 with degrees in Criminology and Political Science and earned his masters and doctorate at Iowa State University in Social Psychology. He is also a member of the American Society of Criminology, the American Psychology-Law Society, and the Western Psychology Association. 


Ph.D., Social Psychology, Iowa State University, Ames, IA

M.S., Social Psychology, Iowa State University, Ames, IA

B.S., Criminology: Forensic Behavioral Science, California State University, Fresno, CA 

B.A., Political Science, California State University, Fresno, CA


Azizian, A., & Ditchfield, R. E. (TBA). Assessing construct validity and field reliability of Stable-2007 scores in a sample of sex offender parolees within California. In prep. 

Ditchfield, R. E., Guyll, M., & Madon, S. (2023). When consequences have weight: Drawing attention to an apparently real future consequence biases eyewitness identification rates. In press, Journal of Behavioral and Social Sciences.

Ditchfield, R. E., Guyll, M., & Madon, S. (TBA). Experimentally testing eyewitness decision-making differences between victims and bystanders. In prep.

Ditchfield, R. E. & Kieckhaefer, J. (TBA). Experimentally testing the effects of procedural justice in police-eyewitness interactions. Ongoing data collection.

Ditchfield., R. E. & Kieckhaefer, J. Misidentifications harm eyewitnesses too: Theoretical and policy considerations for improving distributive and procedural justice in police-eyewitness interactions. In Van Camp, T (pages TBD). In prep. 

Ditchfield, R. E., Suhail, H., & Kafonek, K. Predicting undergraduate perceptions of law enforcement legitimacy and victimization. Ongoing data collection.

Guyll, M., Madon, S., Ditchfield, R. E., & Slapinski, K., More, C., & Burd, K.. Confessions give credibility to otherwise implausible prosecution narratives. In prep.

Kieckhaefer, J., Ditchfield, R. E., Mazon, A., & Burd, K. An experimental examination of the effects of court facility dogs on juror perceptions and decisions in a mock civil trial. Ongoing data collection.

Madon, S., Ferrera, P., Goldstein, A., & Ditchfield, R. E. (2023). The psychology of confession decision making during police interrogation. In M.K. Miller, L.A. Yelderman, J.A. Cantone, & M. Huss (Ed.), Cambridge Handbook of the Psychology of Legal Decision Making. In press, Cambridge University Press.

Madon, S., Scherr, K., & Ditchfield, R. E. (2023). The psychological causes of criminal confessions. In press, Research Handbook in Law and Psychology (Elgar Publishing).

Madon, S., More, C., & Ditchfield, R. E. (2019). Interrogations and confessions. In N. Brewer, & A. Douglass (Ed.), Improving the criminal justice system: Perspective from psychological science. Guilford Press.

Pluta, K., More, K. R., Boyd, A., Le, S., Ozoh, C., Ditchfield, R. E. (2020). From cafeteria to community: Amending the National School Lunch Act to promote healthy eating in children. Journal of Science Policy & Governance, 17(2).

Smith, A. M., Smalarz, L., Ditchfield, R. E., & Ayala, N. T. (2021). Evaluating the claim that high confidence implies high accuracy in eyewitness identification. In press, Psychology, Public Policy and Law.

Vallano, J., Guyll, M., Ditchfield, R. E., & Slapinski, K. (2022). An experimental examination of rapport and minimization within a criminal interview. Psychology, Public Policy and Law, 28(4), 515–531.