Linearity-assumption testing for mental-effort relations

Research Method · All research methods
Evidence · 3 claims (3 for) · 1 study (1 associational), q2 · 0 of 1 report an effect size · 3 claims rest on one study

Description

The article recommends that researchers check whether relations involving self-rated mental effort are linear before fitting and interpreting linear models, because "predictions based on linear models may be substantially biased for most of the range of mental effort". It demonstrates a pragmatic approach: fit competing models of increasing polynomial complexity (none, linear, quadratic, cubic, more complex) in two-level mixed-effects models and compare them on R2M, AIC and BIC. The response-time finding is presented as "a clear example of why testing the linearity assumption and reporting the core outcomes of that check is important".

Accounts

• Test the linearity assumption before reporting linear models for mental-effort relations: The article recommends that researchers check whether relations involving self-rated mental effort are linear before fitting and interpreting linear models, because "predictions based on linear models may be substantially biased for most of the range of mental effort". It demonstrates a pragmatic approach: fit competing models of increasing polynomial complexity (none, linear, quadratic, cubic, more complex) in two-level mixed-effects models and compare them on R2M, AIC and BIC. The response-time finding is presented as "a clear example of why testing the linearity assumption and reporting the core outcomes of that check is important". (Jimmie Leppink et al. (2019))

Claims

• Mental effort relates to response time in a J-shaped quadratic rather than linear pattern [+M]
• Mental effort relates to self-rated certainty in a cubic (declining–flat–declining) rather than linear pattern [+M]
• Mental effort relates to article viewing time linearly; no evidence against the linear model was found [+M]

Related Research Methods

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Key Sources

• Jimmie Leppink & Patricia Pérez-Fuster. (2019). Mental Effort, Workload, Time on Task, and Certainty: Beyond Linear Models. Educational Psychology Review. https://doi.org/10.1007/s10648-018-09460-2

Page metadata

Field	Value
type	research-method
id	linearity-assumption-testing-for-mental-effort-relations
title	Linearity-assumption testing for mental-effort relations
description	The article recommends that researchers check whether relations involving self-rated mental effort are linear before fitting and interpreting linear models, because "predictions based on linear models may be substantially biased for most of the range of mental effort".
status	review
generated	by process:settle-candidates on 2026-10-21
trust	unverified — no one has confirmed this page's content

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