HIGH-FIDELITY PERCEPTUAL LONG-TERM-MEMORY

Visual long-term memory for spatial information was assessed by measur ing discrimination thresholds for the spatial frequency of sinusoidal gratings in a delayed discrimination task, with various time intervals separating test and reference stimuli. The results demonstrate perfec t preservation of information across 1-s to 50-hr retention intervals in the sense that the spatial frequency discrimination thresholds rema ined at the level defined by the spatial resolution of the sensory ana lysis. This high-fidelity spatial long-term memory may represent an el ementary memory mechanism for precategorical storage of visual feature s.