Cognitive Functioning — Performance-Based Assessment
Cognitive Instruments
Stroop, Lexical Decision Task, and Mental Rotation — the performance-based tasks that probe the cognitive apparatuses of the conflict-free sphere.
1. Stroop Color-Word Task
Response inhibition and selective attention. The Stroop paradigm (Stroop, 1935) is one of the most replicated findings in experimental psychology: naming the ink color of a color-word (e.g., the word RED printed in blue ink) is slower and more error-prone than naming the ink color of a non-color-word or a colored patch. The interference effect — typically 50–150 ms — indexes the strength of the automatized reading response relative to the strategic color-naming response.
The Stroop measures inhibitory control: the ability to suppress a prepotent, automatic response in favor of a deliberate one. In CHC terms, it indexes Gs (processing speed) and executive attention within Gf (fluid reasoning). Reduced Stroop performance appears in ADHD, frontal lobe pathology, schizophrenia, depression, and high-anxiety states.
In the ImplicitifyAI implementation, the Color Stroop runs as a Rust→WebAssembly task delivering millisecond-precision reaction times to the scoring server. The interference index is computed as: mean incongruent RT − mean congruent RT.
2. Lexical Decision Task (LDT)
Word recognition speed and semantic priming effects. The LDT (Meyer & Schvaneveldt, 1971) presents strings of letters and requires the participant to decide, as quickly as possible, whether each string is a real word or a non-word. Correct “word” responses to real words and correct “non-word” responses to non-words are analyzed.
Mean correct-trial reaction time (excluding errors and outlier RTs >3 SD) provides a baseline index of lexical access speed. The priming manipulation — measuring RT to a target word that follows a semantically related vs. unrelated prime — indexes the strength of semantic associations in long-term memory.
What LDT reaction time actually indexes: three overlapping processes contribute to LDT RT — visual word recognition (orthographic pattern matching), lexical access (retrieval of the word’s entry from the mental lexicon), and the binary decision process (word vs. non-word judgment). Individual differences in LDT speed reflect all three components.
Try the Lexical Decision Task →3. Mental Rotation
Generating, maintaining, and rotating an internal spatial representation. Shepard and Metzler’s (1971) landmark finding established that mental rotation RT scales linearly with angular disparity: it takes longer to decide whether two objects are the same or mirror images when they are rotated further from each other. This linear relationship — the mental rotation function — suggests that spatial rotation is a genuine analog process, not a feature-matching algorithm.
In CHC terms, mental rotation is a narrow ability within Gv (visuospatial processing). Individual differences in mental rotation performance predict success in geometry, engineering, and surgery. Sex differences in 3D mental rotation performance are among the most reliable findings in cognitive sex-difference research, though the magnitude and interpretation of these differences remain actively debated.
4. Convergence Across Instruments
No single cognitive instrument provides a complete picture of the conflict-free sphere. The Stroop indexes inhibitory control; the LDT indexes lexical access and semantic priming; mental rotation indexes visuospatial capacity. A multi-instrument cognitive battery provides convergent information about processing efficiency across different cognitive systems, and divergences across instruments are diagnostically informative: a participant with fast LDT but slow Stroop may have efficient semantic access but poor inhibitory control — a pattern consistent with ADHD profiles.