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Novel Object Recognition Calculator

Score NOR exploration with the live keyboard scoring pad or enter pre-timed totals. Get Discrimination Index, Preference Index, and group comparisons with error bars.

DI/PI ScoringKeyboard TimerCSV Export
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Load example NOR data to see the full workflow

Session Time

0:00.0

Familiar (F)

0:00.0

Novel (N)

0:00.0

Press Start, then hold F for familiar and N for novel object exploration

  • Score novel object recognition test trials and compute Discrimination Index and Preference Index
  • Live keyboard scoring of familiar vs. novel object exploration during video playback or live observation
  • Compare NOR performance across treatment groups with error bars (mean ± SEM)
  • Quick DI/PI calculation from pre-timed exploration data already collected
  • Export individual and group NOR data to CSV for downstream statistical analysis

Don't use for

  • Automated video tracking of object exploration — use ConductVision or dedicated tracking software for that
  • Object location test or object-in-place test scoring (different paradigms with spatial components)
  • NOR with more than two objects per trial (e.g., recency or temporal order tasks)

What Is the Novel Object Recognition Test?

The Novel Object Recognition (NOR) test was introduced by Ennaceur and Delacour in 1988 as a one-trial learning task that exploits the innate tendency of rodents to explore novelty. In the standard protocol, an animal is first habituated to an open-field arena (habituation phase), then allowed to explore two identical objects during a familiarization (sample) phase. After an inter-trial interval, the animal is returned to the arena where one of the familiar objects has been replaced with a novel object (test phase). Animals with intact recognition memory spend significantly more time investigating the novel object. The NOR test has become one of the most widely used assays in behavioral neuroscience because it is simple, does not require food or water deprivation, avoids aversive stimuli, and is sensitive to hippocampal and perirhinal cortex lesions as well as pharmacological manipulations affecting memory.

The Discrimination Index Explained

The Discrimination Index (DI) quantifies how much an animal prefers the novel object relative to total exploration. It is computed as DI = (novel exploration time - familiar exploration time) / (novel exploration time + familiar exploration time). DI = 0 means equal exploration of both objects (chance performance); DI > 0 indicates novel object preference (intact recognition); DI < 0 indicates familiar object preference (rare, may indicate anxiety or procedural issues). A closely related measure is the Preference Index (PI = novel / total), which ranges from 0 to 1 with 0.5 as chance. Both metrics normalize for individual differences in overall activity levels — an important advantage over raw exploration times. When reporting results, provide both DI (or PI) and total exploration time, because very low total exploration makes the index unreliable. Group data should be reported as mean ±\pm SEM with individual data points visible.

Best Practices for Object Selection and Arena Design

Object selection is the most common source of confounds in NOR studies. Objects must be counterbalanced across animals so that every object serves as both novel and familiar for different subjects — this controls for spontaneous object preference. Objects should differ in shape and color but be similar in size and complexity. Avoid objects with strong odors, sharp edges, or surfaces that allow climbing. The arena should be opaque, well-lit (15-20 lux for standard NOR; dim red light for anxiety-sensitive strains), and cleaned with 70% ethanol or a mild detergent between trials. Place objects equidistant from the walls and from each other. Video-record all sessions and define exploration operationally (e.g., nose directed toward object within 2 cm, excluding sitting on or leaning against the object). Use multiple independent scorers or automated tracking to establish inter-rater reliability. The familiarization phase should provide sufficient exposure (typically 5-10 minutes with two identical copies of the to-be-familiar object) and the test phase should be 5 minutes unless your protocol specifies otherwise.

Frequently Asked Questions

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