Absolute Judgement of 1-D Stimuli

1. Sound Pitches (Pollack): equal logarithmic steps from 100 - 8000 cps. Levels off at 2.5 bits (we can choose 6 pitches which listener will never confuse). Varying range didn't change results appreciably. Persons recognizing 5 high pitches or 5 low pitches didn't recognize 10 when combined.
2. Sound Loudness (Gardner): varying spacing between 15 - 110 dbs. Levels off at 2.3 bits (5 levels).
3. Salinity (Beebe-Center): varying concentration from .3 to 34.7 gm NcCl per 100 cc water. Levels off at 1.9 bits (4 levels).
4. Position on a Line (Hake/Gardner): pointer at arbitrary position between 2 markers. Participants labeled either from a list of possibilities or number between 0 and 100. Levels off at 3.25 bits, though improves some for long exposure (10 - 15 levels).
5. Sizes of Squares (Eriksen/Hake): 2.2 bits
6. Color (Eriksen): 3.1 bits for hue, 2.3 bits for brightness
7. Touch (Gelard): placing vibrators on the chest area. Levels off at 4 intensities, 5 durations, and 7 locations.
8. Line geometry (Pollack): line length was 2.6 - 3 bits (depends on duration), direction was 2.8 - 3.3 bits, curvature was 2.2 bits for constant arc length, 1.6 bits for constant chord length.

Summary: Appears to be some built-in limit on our capability to perceive 1-D signals. Mean is 2.6 bits, standard deviation is .6 bits.