Modality is determined by which of the following?

• A. The cognitive attention to the stimulus
• B. The strength of stimulus alone
• C. The receptor adaptation rate
• D. Receptors and pathway determine the mode of sensation (labeled line coding)

Answer: (D)

Modality of a sensation is determined by which receptor is activated and the neural pathway that carries that signal. This is the idea of labeled-line coding: each receptor type sends its signals along a dedicated pathway to specific brain regions, so the brain interprets the input as touch, temperature, pain, etc., based on the receptor and the route, not just the strength of the stimulus. Receptors for different modalities (mechanical, thermal, chemical, nociceptive) connect to distinct pathways, and that wiring preserves the type of sensation all the way to perception.

The strength of the stimulus affects how intense the sensation feels, not what kind of sensation it is. Attention can influence how noticeable a stimulus is, but it doesn’t change the basic category of sensation. Receptor adaptation changes how quickly a stimulus fades from awareness or how its timing is perceived, again not switching the modality. So the determining factor for modality is the receptor type and its corresponding pathway—the labeled-line code.