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Meet Our Team

Marcy Gunn
Jonathan Cleveland
Ray Oakes
Erika Fontana
Stephen Hamilton
Kathryn Strieff
Gregory Singfield
Linda DeRamus
Kim Yost
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Marcy Gunn, Psy.D.
Owner/Director of Child Psychology
Dr. Gunn is a licensed clinical psychologist who sees individuals of all ages. Having begun with a particular interest in working with children, adolescents and families, she now enjoys seeing clients across the lifespan. She has over thirty years of experience in the Dayton area providing therapy and assessments for a diverse range of needs, and she has been the owner of Cordell Associates, LLC for the past six years. Areas of expertise include treatment of childhood sexual abuse and other traumas; interventions with children who have experienced family disruptions such as divorce and/or foster or kinship care placement; assisting individuals on the autism spectrum and their families; and helping adult women cope through life’s transitions. Dr. Gunn also provides clinical supervision to several of the psychology residents and psychology assistants in the office.
Jonathan Cleveland, Ph.D.
Director of Adult Psychology
Dr. Cleveland (Jon) meets with adults who experienced difficult childhoods. Over the course of treatment, he collaborates with his clients to increase insight, self-esteem, resiliency, flexibility, the ability to trust, as well as the capacity for humor and creative expression. Jon specializes in treating trauma and dissociation using psychodynamic psychotherapy, hypnosis, havening, and EMDR (eye-movement desensitization and reprocessing). For clients wishing to focus on “parts work,” he incorporates ego state and IFS (internal family systems) techniques. He often meets with therapists who are seeking their own psychotherapy or professional consultation and enjoys supervising doctoral students and postdoctoral trainees.

Jon serves on the board of directors for the International Society for the Study of Trauma and Dissociation and is the current chair of membership for the Ohio Psychological Association. He is a clinical faculty member at WSU’s School of Professional Psychology, former editor-in-chief of Trauma Psychology News, and current editor of The Miami Valley Psychologist. In his leisure time, Jon finds himself cooking, reading, and tinkering with synthesizers. He also enjoys playing golf and traveling to new places to ski & scuba dive with friends.
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Ray Oakes, M.A., LPCC-S
Clinical Supervisor
A Dayton resident since 1976, Ray has been affiliated with the practice since 1992. He has worked in partial hospital, intensive residential, outpatient and school settings with a primary focus on children, parenting & family. Consulting with school personnel to support achievement has been a major focus. Family, friends, exercise & social justice are passions that give purpose.
Erika Fontana, M.S.W., LISW-S
Clinical Supervisor
Erika earned her Master of social work degree from the University of Utah and has been a practicing therapist for over 16 years, with much of her focus on clients with trauma and substance abuse issues. She has received training in EMDR, havening, DBT, and seeking safety, and employs these and other treatment modalities including CBT and mindfulness training according to each client’s needs. She has experience working with adults, teens, children, groups, couples and families, and currently works with both adults and adolescents.

Areas of focus: Trauma, mood disorders, anxiety, grief and loss, substance abuse, relationship difficulties, communication skills, parenting skills
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Stephen Hamilton, Ph.D. M.Div.,
Lt.Col. (ret)
Clinical Psychologist
Dr. Hamilton has been practicing with Cordell Associates since 2022. Prior to coming to the practice, he was a staff psychologist at Wright Patterson AFB mental health clinic and faculty member at their APA accredited psychology internship program. Originally from Southern California, he has a combined 32 years of clinical experience, both on active duty and following his retirement, as a civilian psychologist at the Dayton VA and WPat MH clinic. He has been trained in and practiced all the current evidence-based trauma treatments (CPT, PE, EMDR), but has found using the Havening techniques (a new and powerful therapeutic tool to help people recover from painful thoughts, memories, feelings and sensations) to be exceptionally effective. Dr. Hamilton is one of the first certified Havening practitioners and the only trainer in Ohio.

Given his career experiences, he likes working with military members and their families, veterans, first responders, performers, and athletes who seek to perform at a consistently high level under the most challenging conditions and succeed. His clinical interests are sports and performance psychology, anxiety disorders, behavioral health and positive psychology.
Kathryn Strieff, M.S.W., LISW-S
Independent Social Worker
Kathryn has experience and training in a variety of therapeutic approaches, including eye movement desensitization and reprocessing; dialectical behavior therapy; mindfulness; motivational interviewing; cognitive behavioral therapy; and problem solving therapy. To learn more about her philosophy and approach, you mayvisit
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Gregory Singfield, M.A., LMFT
Marriage and Family Therapist
Gregory earned his master’s degree in marriage & family therapy from St. Mary’s University of Minnesota. Prior to joining the Cordell team, Gregory, a relationship therapist, attained a variety of skills that have assisted him in working with couples, families, individuals, the Deaf/Hard of Hearing communities, and others who are working toward managing stress, drug/alcohol difficulties, conflict and personal growth journeys. Gregory is strongly committed to strength-based therapy and is passionate about assisting families in discovering and utilizing strengths while respecting their cultural values throughout the healing process. His specialties include families, couples, adolescents, seniors, emotional regulation, relationship difficulties, Deaf and Hard of Hearing, substance use disorders, parenting, and group therapy.
Linda DeRamus, Ph.D.
Psychology Resident
I love working in the field of psychology. Not yet licensed in the state of Ohio, I work at Cordell Associates as a psychology resident. It is a privilege to connect with people in their most honest and raw moments. I hold people’s pain with the utmost compassion and care. I hope the process of therapy helps you to increase your compassion for yourself. Sometimes therapy can imply that something is wrong and needs to be fixed. I prefer to think of therapy as a means to support one another in the path of life-long personal growth as we work together to resolve difficulties in the most enlightened ways possible.

Over the past 37 years, I have worked in a variety of settings, including inpatient psychiatric hospitals in Ohio and California, outpatient psychiatry in California and Kaiser Permanente, and in Hawaii as a director of mental health, overseeing mental health care of children, teens, young adults and families in Maui. At Cordell Associates, I focus on treating people who struggle with depression, anxiety, low self-esteem, trauma symptoms, eating and body image issues, relationship conflicts, difficulties with employers, obsessive compulsive disorder, and more serious difficulties. I look forward to connecting with you soon.
Kim Yost, B.A.
Pre-intake Specialist
Kim conducts pre-intake phone calls at Cordell Associates. He earned his bachelor’s degree in philosophy from Wright State University and is currently studying clinical mental health counseling at Liberty University.  Kim enjoys cooking, cycling, gardening, and spending time with loved ones. 
Jessica Hubbell, M.A.
Predoctoral Resident

Jessica Hubbell is a psychology resident in the final stage of completing her dissertation and doctorate in school psychology from Michigan State University. Jessica has extensive experience with assessment, creating and implementing behavioral plans, and consulting on system-level interventions. Jessica also has experience working in a state-run psychiatric hospital, consulting with psychiatrists, and providing outpatient psychotherapy to diverse patients.


Currently, she works with children, adults, and families. Jessica strives to create a comfortable, accepting, educational, and fun environment! Her preferred psychotherapeutic modalities are CBT, CPT, PCIT, and DBT. She is also being trained in EMDR and IFS. Jessica’s areas of focus are trauma (children and adults), social skills, parenting skills, relationship difficulties, communication skills, anxiety, depression, mood disorders, and parent/child relationships.

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Aroosa Syed, Psy.M., M.S.
Psychology Assistant
Aroosa is a 5th year doctoral student at Wright State University’s School of Professional Psychology. Aroosa received her master’s degree in Clinical Psychology from Wright State University and her master’s degree in educational psychology from University at Albany. She received her bachelor’s degree in psychology from Buffalo State College. Her clinical interests include trauma, anxiety, depression, family/parenting, multicultural identity formation and assessment. She has been a trainee at Resilient Young Ladies and Gentlemen(RYLM), and Child Focus where she worked with young adults and provided individual and group therapy. Aroosa is skilled in cognitive, academic achievement, and personality assessments for both adults and children. Her research interests include emotion dysregulation in adolescents and different issues related to discrimination and racism. She typically takes a cognitive behavioral and feminist psychology approach to treatment. She has been enjoying working in private practice where she has been able to form meaningful connections and further develop her clinical abilities.
Vanessa Prosper, Psy.M.
Psychology Assistant
Vanessa is a 4th-year clinical psychology doctoral trainee at Wright State University’s School of Professional Psychology, where she received her master’s degree in clinical psychology and is pursuing a doctoral degree. She received her bachelor's degree in psychology from the University of South Florida with a minor in applied behavioral analysis. Her clinical interests include trauma, anxiety, depression, relationship concerns, mindfulness practice, assessment and racial trauma. Vanessa enjoys working with a wide variety of clients and diagnoses. She uses an integrative approach to treatment with a basis in client centered feminist theories. This allows her to center client's needs in treatment, address client's own capabilities to make changes, address systems that impact client's well-being and incorporate other evidence-based approaches towards
client's goals.
Elizabeth Thomsen, Psy.M.
Psychology Assistant

Liz is a third year Psychology Trainee at Wright State University’s School of Professional Psychology. Her professional interests include psychological assessment and psychotherapy with youths and adults. Her clinical interests include learning disorders, ADHD, academic struggles, anxiety, depression, and trauma. Liz works from a person-centered lens that incorporates a social-cognitive perspective and is passionate about helping people connect with their personal strengths and gaining trust in themselves.  


Prior to pursuing her doctoral degree, Liz lived in Portland, Oregon where she earned her Bachelor of Science in psychology at Portland State University. She served her Pacific Northwest community through community mental health and crisis work, while also contributing to and leading research projects at the Center for ADHD Research at Oregon Health and Science University. Liz loves being outdoors and spending time with friends and family. She spends her free time skateboarding, swimming, camping, and hiking.   

Alana Holsapple, Psy.M.
Psychology Assistant
Alana Holsapple is a 3rd year Psychology Trainee at Wright State University School of Professional Psychology. She received her bachelor’s degree at Bluffton University, where she also played NCAA volleyball. Alana’s clinical interests include therapy and assessment with children and adolescents with anxiety disorders, OCD, grief, and trauma. Her continued goals are to learn and utilize a variety of measures of assessment for diverse populations and implement play therapy techniques into treatment. She works from an integrated CBT, ACT, and strength-based lens to encourage acceptance and empowerment among clients. She previously worked at Dayton Job Corps where she practiced short-term therapy for adolescents and young adults on center. In her free time, Alana likes to listen to music, cook new foods, bike, play volleyball, and go on walks with her dog, Lily.
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Jaden Johnson, Psy.M.
Psychology Assistant
Jaden Johnson is a clinical psychology student who is working as a therapist at Cordell Associates. She has interests in working with children and adolescents with a variety of mental difficulties. Jaden has experience with conducting psychological assessments and working with all ages of clients. She has a special interest in animal assisted therapy which is what she hopes to incorporate in her work once she finishes school. Jaden is eager to help her clients reach their goals and aid in their therapeutic journey!
Misty Brown, M.S.W.
Social Work Trainee
Misty brings with her 38 years of experience as a holistic wellness practitioner who integrates traditional therapeutic modalities with sound of vibrational therapy, somatic therapy and therapeutic art. She is in the process of completing her master’s degree in social work. Misty founded and operates Love Shack (offering free wellness and counseling services) and is known for her work as a community wellness advocate, connecting at risk communities in the Dayton area with services, education and resources since the tornadoes of 2019.
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Sherry West
Office Manager
Sherry West has been the office manager at Cordell Associates since 2013. A native to the area, she attended Beavercreek High school and graduated from Greene County Career Center’s medical/legal program. In her role at Cordell Associates, she oversees the front office, from coordinating staff and clinicians, to scheduling new and existing clients, managing payroll to creating quarterly stat reports. She also oversees the credentialing process and much more. In her spare time, Sherry enjoys being with her husband, Greg, and their 12 grandchildren in the outdoors, from gardening to hiking.
Tiffany Davis, LSW
Licensed Social Worker
I am an LSW working on my Master's at OSU and completing my practicum here at Cordell. Prior to this placement, I provided therapy services to adolescents in school and in the juvenile justice system. I currently hold a position in Franklin County where I complete community crisis assessments and provide linkage. My professional goals include gaining my animal assisted therapy certification and opening my own therapy farm at some point. I am engaged and have 2.25 dogs (two are big and one is tiny) and 4 cats currently. I like to hike, be outside, spend time with my animals, draw, paint, get tattooed and change my hair color every few months. 
Jessic Hubbell
Aroosa Syed
Aroosa Syed
Jaden Johnson
Alex Sheppard
Misty Brown
Sherry West
Debbie Miles
Administrative Assistant
Nancy Brown
Administrative Assistant
Keith Alford
Billing Coordinator
Sherry West
Office Manager
Sheila Shell
Administrative Assistant
Kim Yost
Pre-intake Specialist
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