- Duration, capacity and encoding
Duration: LTM unlimited, STM measured in seconds
- Shepard - 50% of photos recalled after 4 months
- Bahrick et al. - Yearbook photos, recall 70% accurate after 48 years
- Peterson and Peterson - constanant syllables, max 18 seconds
- Marsh et al. - duration may be only 2 seconds if no expection of recall.