Abstract
We know that observers can typically discriminate old images from new ones with over 80% accuracy even if after seeing hundreds of objects for just 2-3 seconds each (“Massive Memory”). What do they know about WHERE and WHEN they saw each object? From previous work, we know that observers can remember the locations of 50-100 out of 300 items (Spatial Massive Memory – SMM). In a different study, observers could mark temporal locations within 10% of the actual time of the item's original appearance (Temporal Massive Memory - TMM). Are SMM and TMM related? In new experiments, 64 observers saw 50 items, each sequentially presented in random locations in a 7x7 grid. They subsequently saw 100 items (50 old). Four sets of instructions were used: (1) Mere Identity instruction asked 16 observers just to remember the items. (2) Spatial instruction asked 16 observers to also remember item locations. (3) Temporal instruction asked 14 observers to remember when items appeared. (4) Full instruction (13 observers) combined Spatial and Temporal instructions. At test, observers in all conditions were told to click on the original location of old items and to indicate when they saw it on a time bar. ~12% of observers appeared to guess on the spatial task and ~50%(!) guessed on the timing task. Interestingly, just 6% guessed on both, exactly as would be predicted if the choice to guess was independent for space and time. Overall, space and time scores were strongly correlated for Full Instructions (r-sq=.64, p=0.001), Temporal (r-sq=.31, p=0.04), and marginally correlated for Spatial (r-sq=.20, p=0.08). The Mere Identity correlation was insignificant (r-sq=.03, p=0.40). Effects of instruction on performance were generally insignificant. Observers can have quite good memory for when and where they saw an object. Those memories seem to be modestly correlated with each other.