Stimulus Discrimination

This resource helps clients distinguish between past trauma and present safety, reducing distress related to trauma triggers.

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Professional version

Offers theory, guidance, and prompts for mental health professionals. Downloads are in Fillable PDF format where appropriate.

Client version

Includes client-friendly guidance. Downloads are in Fillable PDF format where appropriate.

Editable version (PPT)

An editable Microsoft PowerPoint version of the resource.

Overview

Stimulus discrimination - often referred to as 'then vs. now' - is a therapeutic exercise designed to help trauma survivors differentiate between past traumatic events and present safety. By focusing on current sensory experiences and comparing them with past trauma, clients can reduce involuntary and distressing trauma recollections. This method is particularly effective in reducing symptoms of PTSD, helping clients realize (cognitive and then emotionally) when they are genuinely safe, and mitigating avoidance behaviors.

Why Use This Resource?

Stimulus Discrimination offers a structured approach for clients to manage involuntary trauma memories, promoting a sense of safety in the present.

  • Helps clients to distinguish between past trauma and current safety.
  • Reduces distress caused by trauma triggers.
  • Encourages clients to focus on differences between past and present.

Key Benefits

Insight

Enhances awareness of present safety versus past trauma.

Practicality

Provides a tangible technique for in-session and at-home use.

Empowerment

Empowers clients to manage their trauma responses actively.

Who is this for?

Post-Traumatic Stress Disorder (PTSD)

Re-experiencing symptoms and avoidance related to trauma triggers.

Integrating it into your practice

01

Record

Note the situation when the trauma memory was triggered.

02

Similarities

Identify similarities between current experience and past trauma, work across sensory modalities.

03

Differences

Focus on differences between current experience and past trauma, work across sensory modalities.

04

Focus

Direct attention to present sensory details to highlight differences.

05

Reassure

Encourage self-soothing and affirm current safety.

06

Reinforce

Use these insights to reduce future trauma reactions.

Theoretical Background & Therapist Guidance

Stimulus discrimination is grounded in cognitive and neurobiological understandings of trauma, particularly how trauma-related memories are reactivated by environmental cues. According to Ehlers and Clark’s (2000) cognitive model of PTSD, distress persists when individuals misinterpret trauma reminders as indicators of current threat. This happens through stimulus generalization, where neutral or safe cues that resemble elements of the traumatic event evoke intense emotional responses.

Stimulus discrimination addresses this process by helping clients systematically attend to the differences between past trauma cues and the current environment. By contrasting sensory information across modalities — what they see, hear, smell, feel, and even their internal bodily states — clients can reappraise present experiences as safe rather than threatening.

This approach is consistent with dual representation theory (Brewin, Dalgleish, & Joseph, 1996), which posits that trauma memories are stored in two systems: verbally accessible memory (VAM) and situationally accessible memory (SAM). Triggers often activate SAM, resulting in vivid and intrusive re-experiencing. Stimulus discrimination supports access to VAM, allowing clients to contextualize their memories and distinguish between “then” and “now”.

Neuroscience research also supports this framework. Findings from studies on fear extinction and context processing (e.g. Milad et al., 2007) suggest that the ability to recognize contextual differences is central to reducing conditioned fear responses. Stimulus discrimination may activate the prefrontal cortex, facilitating top-down regulation of the amygdala’s fear responses, and helping consolidate learning that the present is safe.

What's inside

  • A detailed guide for conducting stimulus discrimination.
  • Worksheet for documenting triggers, similarities, and differences.
  • Instructions for emphasizing sensory and context differences.
  • Therapist tips for maximizing patient engagement and outcome efficacy.
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FAQs

Stimulus discrimination is an exercise that helps clients distinguish between past trauma and the safety of the present by focusing on sensory differences.
Unlike exposure therapy, which seeks habituation to distressing stimuli, stimulus discrimination focuses on identifying safety cues in the present to combat fear.
The exercise is designed for ease of use both in therapy sessions and independently, fostering empowerment and skill development.
Yes, it integrates well with cognitive-behavioral approaches and other trauma-focused therapies.

How This Resource Improves Clinical Outcomes

This resource improves clinical outcomes by:

  • Enhancing clients' ability to differentiate past and present contexts.
  • Reducing avoidance and maladaptive behaviors associated with trauma.
  • Increasing self-efficacy in managing trauma-related distress.
  • Supporting therapeutic engagement through a structured, practical approach.

References And Further Reading

  • Brewin, C. R., Dalgleish, T., & Joseph, S. (1996). A dual representation theory of posttraumatic stress disorder. Psychological Review, 103(4), 670-686. https://doi.org/10.1037/0033-295X.103.4.670
  • Ehlers, A., & Clark, D. M. (2000). A cognitive model of posttraumatic stress disorder. Behaviour Research and Therapy, 38(4), 319-345. https://doi.org/10.1016/S0005-7967(99)00123-0
  • Milad, M. R., Pitman, R. K., Ellis, C. B., Gold, A. L., Shin, L. M., Lasko, N. B., & Rauch, S. L. (2009). Neurobiological basis of failure to recall extinction memory in posttraumatic stress disorder. Biological Psychiatry, 66(12), 1075-1082. https://doi.org/10.1016/j.biopsych.2009.06.026