Sensory memory is our ability to retain impressions of sensory information after the original stimulus has ceased.

One of the earliest investigations into this phenomenon was in 1740 by Johann Andreas Segner (1704 - 1777) the German physicist and mathematician. In an elegant experiment Segner attached a glowing coal to a cartwheel and rotated the wheel at increasing speed until an unbroken circle of light was perceived by the observer. He calculated that the glowing coal needed to make a complete circle in under 100ms to achieve this effect. Events May 31 - Friedrich II comes to power in Prussia upon the death of his father, Friedrich Wilhelm I. October 20 - Maria Theresia of Austria inherits the Habsburg hereditary dominions (Austria, Bohemia, Hungary and present-day Belgium). ... Events Building of the Students Monument in Aiud, Romania. ... 1777 was a common year starting on Wednesday (see link for calendar). ... A physicist is a scientist trained in physics. ... This article is in need of attention from an expert on the subject. ...

Sperling ran a more systematic study of this effect in 1960. His experiment involved briefly presenting a grid of three rows of four letters for 50ms to volunteers: 1960 (MCMLX) was a leap year starting on Friday (link will take you to calendar). ...

DHFG
VJSA
LKOP

In one condition he asked participants to report as many letters as they could remember after the letters had been presented. In another he indicated, after the presentation of letters, which row of letters (first, second or third) he would like participants to try to recall. Sperling found that whilst participants could only report an average of four letters in the first condition, they usually successfully recalled the four letters of the chosen row in the second condition, even though they were only told which to report after the whole letter grid was presented. This suggests that for a brief period of time the whole grid was accessible to the participants as sensory memory.

Sensory memory is still considered to operate within this approximate time frame (under 1 second and certainly no more than 2) and so can be seen to be very short lived. It is also characterised by being outside of conscious control (i.e. it happens automatically and unbidden). Despite retaining information for a very short period if time, it is not to be confused with short term memory (which typically lasts 10-15 seconds without rehearsal of the remembered material) and is so named to distinguish it from long term memory which can store information for as long as a lifetime. Consciousness is a quality of the mind generally regarded to comprise such key features as subjectivity, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and ones environment. ... Short-term memory, sometimes referred to as primary or active memory, is that part of memory which stores a limited amount of information for a limited amount of time (roughly 30-45 seconds). ... Long-term memory (LTM) is memory that lasts from days to years. ...

Visual sensory memory is more commonly referred to as iconic memory. Auditory sensory memory is known as echoic memory. Visual perception is one of the senses, consisting of the ability to detect light and interpret (see) it as the perception known as sight or naked eye vision. ... Iconic memory is a form of memory in which objects are remembered as an icon. ... Hearing, or audition, is one of the traditional five senses, and refers to the ability to detect sound. ...

See also

• iconic memory
• memory
• visual perception

Iconic memory is a form of memory in which objects are remembered as an icon. ... Memory is the ability to retain information, a faculty of the brain. ... Visual perception is one of the senses, consisting of the ability to detect light and interpret (see) it as the perception known as sight or naked eye vision. ...

References

• Sperling, G. (1960) The information available in brief visual presentations. Psychological Monographs: General and Applied, 74, 1-29.