Sensation, Thresholds, and Psychophysics (6A) Practice Test

In a study of absolute threshold for detecting a faint vibration from a smartphone (200 Hz), participants rested their index finger on a haptic pad in a quiet room. The vibration amplitude was adjusted using a staircase procedure, and the intensity at which the participant reported feeling the vibration on 50% of trials was recorded as threshold. Participants were randomly assigned to either a "no distraction" condition or a "texting" condition in which they silently composed a message during testing. Mean thresholds were higher in the texting condition. What conclusion is most consistent with the concept of absolute threshold in this vignette?

A consumer-safety team tested whether drivers notice a small change in dashboard warning tone loudness, focusing on the difference threshold. Drivers heard two tones in succession while viewing a simulated road scene; the first tone was the standard. In one condition the standard was 30 dB; in another it was 60 dB. The JND (smallest increase reliably judged as louder) was 3 dB at 30 dB and 6 dB at 60 dB. Which interpretation best applies difference-threshold reasoning to this real-world context?