What is identity matching? Identity matching is a matching-to-sample performance in which the selected comparison is physically identical to the sample. A red triangle is matched to the same red triangle, or a photograph to an identical copy. Assessment varies samples, comparison positions, distractors, and examples while defining independent responses, prompts, omissions, invalid trials, and access supports. Correct selections should follow sample identity rather than position or another unintended feature.
The sample determines the identical choice
On each trial, a sample appears with two or more comparisons. One comparison is the same stimulus as the sample. When the sample changes, the correct comparison changes too.
This sample-comparison dependency distinguishes conditional discrimination from a simple preference for one item or location. Repeatedly selecting the left card can produce some correct responses without identity control.
Physical identity is the defining relation
The sample and correct comparison share the relevant physical properties. Depending on the question, they may be identical objects, pictures, shapes, sounds, textures, or other accessible stimuli.
If the sample is the printed word “shoe” and the comparison is a shoe photograph, the relation is arbitrary rather than identity matching. If the sample and comparison share only color while differing in form, the task may be matching by a common feature.
Identity matching differs from reflexivity tests
Identity matching can be directly taught and reinforced. Reflexivity in stimulus-equivalence assessment refers to an emergent identity relation demonstrated without direct training of those exact identity matches under the relevant test.
The visible trial can look similar in both cases. The training history and probe conditions determine what the result can show.
Build balanced trials
Define the sample, comparison array, correct identity, distractors, response, response window, prompts, consequence, and error procedure. Balance correct comparison positions across samples.
Choose distractors that answer the intended question. If the correct comparison is the only large or brightly colored item, a correct response may reflect that feature instead of identity.
A fictional example
Mei chooses to practice matching six workplace supply labels. Each trial presents one sample label and three comparison labels. Every sample appears four times, and the correct position is balanced across the 24 trials.
Mei responds correctly on 20 of 24 independent trials, or 83.3%. Three of four errors occur when the correct comparison is on the left. Since left placements were correct equally often, the team examines which sample features appeared in those trials rather than assuming a position bias.
On eight trials with new copies printed on different paper, she responds correctly on 5 of 8. Acquisition and novel-example performance remain separate results.
Control instructor and material cues
An instructor can cue the answer through gaze, hand position, timing, or voice. Materials can carry wear marks, shadows, borders, or fixed spatial patterns.
Use prepared trial orders, neutral presentation, balanced positions, and procedural-integrity samples. When video is used, obtain required consent, limit capture, use approved secure systems, and document access and retention.
Expand from simple to conditional discrimination carefully
A study of identity matching in preverbal children evaluated a progressive route from simple discrimination and reversals to identity matching with alternating samples. It demonstrates one research procedure rather than a universal teaching sequence.
Before changing a program, inspect prerequisite attending, visual access, motor response, discrimination history, reinforcer effectiveness, and procedural integrity. A low score can reflect the task arrangement.
Test new examples and natural use
Mastery with one card set does not establish identity matching across novel objects, sizes, orientations, devices, or settings. Reserve examples for generalization probes and label them before teaching.
Connect the task to a useful outcome. Matching identical laundry symbols, device icons, forms, or personal belongings may matter; abstract card matching may not be a priority for every person.
Accessibility changes the form, not the principle
Use visual, auditory, tactile, or multimodal stimuli that the person can reliably access. Provide positioning, lighting, contrast, device access, wait time, and an effective response method.
Keep augmentative and alternative communication and other essential supports available. Record adaptations so another reviewer can understand what was tested.
The BACB outline sets a broad learning target
The BACB BCBA Test Content Outline includes stimulus control, discrimination, conditional-discrimination procedures, and emergent relations. It is examination content and does not prescribe a client's goal or method.
A qualified clinician should interpret performance within assessment, evidence, client preference, context, and scope.
A useful data record includes
- exact samples, comparisons, and matching relation
- trial order and position-balancing method
- opportunity and response definitions
- independent, prompted, incorrect, omitted, and invalid trials
- distractor features and error patterns
- trained versus novel examples
- access supports and procedural integrity
- raw counts, percentages, and practical outcome
Avoid pooling relations or sets that answer different questions.
Related terms
Sources
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