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Optimal stimulation theory

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Summary

  • Theory: low stimulation is harder to bear with ADHD; motion or sound can raise alertness to useful levels on dull tasks.
  • On lab attention tasks, white noise and pink noise slightly help people with ADHD and slightly hinder those without it.
  • Stimulation has an upper limit. The same noise helps some people and hinders others; reduce it if performance worsens.

Restlessness may be a way to add stimulation

Proposed in research

Optimal stimulation theory proposes that doing tasks requires a suitable amount of sensory stimulation to maintain appropriate arousal. Arousal means the current level of wakefulness and alertness. People with attention-deficit/hyperactivity disorder (ADHD) find low stimulation harder to tolerate. During monotonous tasks, leg bouncing or handling objects may add stimulation(Zentall, 1975; Zentall et al., 1985); attraction to novelty is also seen as the same need(Zentall & Meyer, 1987).

Rotz and Wright also propose that restlessness helps people feel more alert and focus, rather than relax(Rotz & Wright, 2005). However, insufficient stimulation does not explain all fidgeting.

Add stimulation to monotonous tasks

Proposed in research

Alongside clearing the environment, the task itself can offer more stimulation. In Zentall’s experiment, adolescents with more attention problems copied better when letters were printed in color; controls showed no such improvement(Zentall et al., 1985). When repetitive tasks used hands-on responses, children with ADHD showed fewer impulsive errors, vocalizations, and restless movements, reaching the same levels as peers(Zentall & Meyer, 1987).

The theory therefore questions relying solely on reducing external distractions and minimizing environmental stimulation(Zentall, 1975).

White noise and pink noise offer a small benefit for ADHD

Research-backed

A meta-analysis combined 13 studies involving 335 children and college students. During laboratory attention tasks, white noise or pink noise slightly improved performance in people with ADHD. Comparing randomly selected people with and without noise, the listener had about a 57% chance of performing better (an approximation)(Nigg et al., 2024).

The same noise slightly worsened performance in people without ADHD: the listener had only about a 44% chance of performing better (an approximation). Pink noise sounds like rainfall. No research has tested brown noise yet(Nigg et al., 2024).

Stimulation has an upper limit; adjust it based on performance

Proposed in research

“Optimal” means adjusting stimulation to a suitable level, not adding as much as possible(Zentall, 1975). Söderlund and colleagues also propose that only moderate noise helps thinking(Söderlund et al., 2007).

In one study, 43 children with ADHD did memory tasks with noise; there was no significant overall effect. Children with relatively more inattentive traits performed better, while those with relatively more hyperactive and impulsive traits performed worse(Söderlund et al., 2024). After adding noise, performance should guide adjustments: reduce it if performance worsens.

Evidence

Emerging evidence

References (7)
  1. TheoryOptimal stimulation as theoretical basis of hyperactivityZentall S (1975). American Journal of Orthopsychiatry
  2. Cohort studyEffects of color stimulation and information on the copying performance of attention-problem adolescentsZentall SS, Falkenberg SD, Smith LB (1985). Journal of Abnormal Child Psychology
  3. Cohort studySelf-regulation of stimulation for ADD-H children during reading and vigilance task performanceZentall SS, Meyer MJ (1987). Journal of Abnormal Child Psychology
  4. BookFidget to Focus: Outwit Your Boredom: Sensory Strategies for Living with ADDRotz R, Wright SD (2005). iUniverse
  5. Meta-analysisSystematic Review and Meta-Analysis: Do White Noise or Pink Noise Help With Task Performance in Youth With Attention-Deficit/Hyperactivity Disorder or With Elevated Attention Problems?Nigg JT, Bruton A, Kozlowski MB, Johnstone JM, Karalunas SL (2024). Journal of the American Academy of Child and Adolescent Psychiatry
  6. Cohort studyListen to the noise: noise is beneficial for cognitive performance in ADHDSöderlund G, Sikström S, Smart A (2007). Journal of Child Psychology and Psychiatry
  7. Cohort studySensory white noise in clinical ADHD: Who benefits from noise, and who performs worse?Söderlund GBW, Hadjikhani N, Thorsson M, E-Said S, Claesdotter-Knutsson E, Gustafsson P, Johnels JÅ (2024). Scandinavian Journal of Child and Adolescent Psychiatry and Psychology