Iconic Memory - Overview

Overview

The occurrence of a sustained physiological image of an object after its physical offset has been observed by many individuals throughout history. One of the earliest documented accounts of the phenomenon was by Aristotle who proposed that afterimages were involved in the experience of a dream. Natural observation of the light trail produced by glowing ember at the end of a quickly moving stick sparked the interest of researchers in the 1700s and 1800s. They became the first to begin empirical studies on this phenomenon which later became known as visible persistence. In the 1900s, the role of visible persistence in memory gained considerable attention due to its hypothesized role as a pre-categorical representation of visual information in VSTM. In 1960, George Sperling began his classic partial-report experiments to confirm the existence of visual sensory memory and some of its characteristics including capacity and duration. It was not until 1967 that Ulric Neisser termed this quickly decaying memory store iconic memory. Approximately 20 years after Sperling’s original experiments, two separate components of visual sensory memory began to emerge: visual persistence and informational persistence. Sperling’s experiments mainly tested the information pertaining to a stimulus, whereas others such as Coltheart performed directs tests of visual persistence. In 1978, Di Lollo proposed a two-state model of visual sensory memory. Although it has been debated throughout history, current understanding of iconic memory makes a clear distinction between visual and informational persistence which are tested differently and have fundamentally different properties. Informational persistence which is the basis behind iconic memory is thought to be the key contributor to visual short term memory as the precategorical sensory store.