Iconic Memory And How It Works
Updated August 03, 2020
Medically Reviewed By: Wendy Boring-Bray, DBH, LPC
Iconic memory plays just one small part in your overall memory tasks and banks. Iconic memory is not something that is typically lost with memory loss, although its role in creating new memory is significant. Iconic memory lasts only milliseconds, but it plays a role—a significant one—in processing what you see and using that information to form new memory.
What Is Iconic Memory?
Iconic memory is a form of sensory memory that stores visual short term impressions and sensations. Sensory memory is ultra-short-term memory that lasts only milliseconds for most people following stimulus offset or onset. Iconic memory is the sensory memory related to visual memory, and might also be called “visual short term memory.” It is called iconic because of icons, or pictures that your brain takes of things that you see, as visual scenes are used to round out immediate perceptions and reach conclusions regarding visual cues.
Some people confuse iconic memory with photographic memory. While there is little evidence that photographic memory is real—and if it is real, how exactly it works—iconic memory is definitive, with a wide body of research. Photographic memory is the ability to see something and remember it from a brief image alone. Iconic memory is simply your brain's way of processing visual information via the initial display of any given visual stimuli.
Iconic memory does not last long, as is evidenced by many studies. You can see iconic memory at it's best through a simple exercise. Close your eyes for a few seconds. Open your eyes for one or two seconds (just long enough to focus on an object) then close them again. For a very brief time, you will still see the image in your mind's eye. That is iconic, visual short term memory at work, keeping the image alive for a brief time after stimulus offset.
There are three types of persistence that occur with visual stimuli and iconic memory tasks: neural persistence, visible persistence, and informational persistence. Neural persistence occurs when neural activity continues after the stimuli is gone. Visible persistence is when you continue to see the image after it is gone, such as with a bright flash of light. Informational persistence is when information about the visual stimuli is still available to the person for some time after the stimuli is gone. Studies in the past have concluded that these three forms of visual persistence rely upon one another and are the source of visual information relayed after offset of stimulus in studies about visual persistence. However, new research has found that this is not the case.
According to newer studies, there are two phenomena that consistently occur with visual stimuli: the inverse duration effect, which means that the longer a stimulus lasts, the briefer its persistence is after stimulus offset, and the inverse intensity effect, which describes how the more intense the stimulus is, the shorter the persistence lasts. These effects happen unless the stimuli are so intense that they produce after images. This is thought to occur in conjunction with neural persistence.
Informational persistence is what makes up iconic memory. Informational persistence has distinctly different properties than visible or neural persistence, as both visible and neural persistence rely heavily upon the visual cortex. Informational persistence does not rely as heavily on the visual cortex, as it converts the visual display to abstract ideas and information, instead of a simple image.
This same study also concluded that iconic memory is not directly tied to the processes of the visual system. The study suggests that iconic memory is post-categorical, and occurs after stimulus identification. The stimulus identification is an automatic process but does not provide episodic properties. In short, the new view is that physical stimulus must be temporarily attached to a representation of the visual stimulus in semantic memory. This temporarily attached information is what constitutes iconic memory.
Iconic memory decays rapidly after the visual stimulus is no longer present. Iconic memory is regarded by most to allow for perceptual integration of two or more images, even if separated by a brief period of time. Many studies have been conducted to determine the duration of iconic memory, usually after the stimulus has been removed (called stimulus offset).
However, a new study has come to light in which it was hypothesized that iconic memory has a set temporal property starting from the onset of the visual stimulus, regardless of how long the stimulus is displayed. This would account for the inverse action of the iconic memory lasting for a briefer period of time with longer duration. The previous studies were measuring the duration of iconic memory from stimulus offset, but the new study measures it from stimulus onset.
The results of the new study seem conclusive, showing that regardless of how long visual stimulus is displayed iconic memory has a fairly set duration. Most often the duration of iconic memory is less than one second. Iconic memory is extremely brief. Only when iconic memory is put into context in the brain and relegated to short term memory does the information persist beyond the single second associated with visual short term memory.
One of the findings that has come up in repeated research about iconic memory is the inability to detect changes in a visual field. Visual change detection has been evaluated in many experiments eager to determine the duration of iconic memory through change detection tests. The subject is given an array of items, then a brief time later, given the same array slightly changed, and asked to determine the change. In most cases, the subjects are unable to determine the change that was made. These findings suggest that change detection is far more difficult than might have originally been expected, and may not be a part of the memory tasks associated with iconic memory and visible changes.
A new study set out to determine why this happens. The common thought is that a serial search of all of the objects is necessary to determine the change, and the iconic memory of the first array fades before that can take place. However, the new study found that it is much more likely that iconic memory can only hold one array at a time. When the new array is presented, it overwrites the information from the first array. Because the memory tasks associated with iconic memory are so brief, it stands to reason that the visual cortex and brain’s processing centers do not hold onto a large number of visual presentations, in order to engage in visual change detection.
Iconic memory is so brief and fleeting that it can only hold a small, limited amount of information for an infinitesimal amount of time. The only way to increase the memory of a visual array is to focus one's attention on the array, which moves the information from iconic memory to short-term memory. Because the short-term memory bank requires attention, focusing in on a visual display and trying to discern information from that display shifts the mechanism being used from the iconic memory researched by George Sperling to the banks of an individual’s short-term memory.
Transfer To Durable Storage
Many studies have been done to determine the rate of transfer of information from iconic memory to durable storage, or short-term and long-term memory. Most studies have found that it takes significant attention to move information from iconic memory to durable storage. Without focused attention, the iconic memory fades rapidly and is not put into a context that commits it to more durable memory. The amount of information that can be moved from iconic memory to durable storage is limited by the capacity of the short-term memory and the availability of iconic memory. Change blindness limits some of the information that is stored, as iconic memory is not able to detect change.
Another study done by the NIH showed that iconic memory, with attention, could be transferred to visual working memory, which lasts several seconds. Visual working memory is a function of short-term memory. This memory in turn only lasts seconds, less than a full minute, without being transferred again to long-term memory. Memory and visible persistence are entirely reliant upon iconic memory and visual working memory; without these two banks to briefly act as a store of visual information, perceptions and images would not move to short-term or long-term memory.
The Brain And Iconic Memory
The primary part of the brain that is involved in iconic memory is the occipital lobe, which is home to the primary visual cortex. The occipital lobe and its primary visual cortex are responsible for processing and regulating visual information. The visual stimulus travels from the visual system of the eyes to the occipital lobe, where it is stored for mere milliseconds, before being discarded or transferred to the temporal lobe. The hippocampus within the temporal lobe is primarily responsible for then converting that memory from short-term to long-term memory.
The Path Of Visual Memory
The path of visual memory is one that is traveled extremely quickly. Iconic memory, visual working memory, and short-term memory have limited capacities and brief temporal characteristics, some of them housed within the primary visual cortex. Only by moving information all the way through the process to long-term memory can visual stimulus be remembered for more than a few minutes; iconic memory requires attention and focus to transfer information to longer-term memory banks.
Presentation Of Stimuli
The first thing that must happen, of course, is for visual stimuli to be presented. Visual stimulus is processed by the visual system and the occipital lobe. Automatic recognition occurs, and it is then placed into iconic memory. This happens very quickly—the magical number is said to be as little as one second in iconic memory, and less than 1 minute in visual working memory.
Once the stimulus has initially been presented, iconic memory begins. The automatic recognition of the visual stimulus display is processed by the occipital lobe and transferred to iconic memory, where it remains for only milliseconds before being transferred to visual working memory or being discarded.
Visual Working Memory
From iconic memory, the information moves to visual working memory. This is like an extremely short term memory in vision and visual stimuli. Visual working memory can last for several seconds. In order for information to move to visual working memory, the subject must have focused attention on the visual display or set of information.
Short Term Memory
The short-term memory lasts only a few minutes and has limited capacity. With focused attention and interrelated memories and thought, visual working memory can be transferred to short-term memory. There, the information remains for several minutes before being discarded or being shuffled along to long-term memory.
Long Term Memory
Long-term memory can be a confusing term. When most people think of long-term memory, they think of things that they remember for years. However, long-term memory doesn't necessarily last forever in human neuroscience. It does decay over time, depending on how frequently you access the information. If information from iconic memory is to last beyond a few minutes, it needs to be stored in long-term memory.
Getting Help With Failing Memory
If you find that you can't remember things that you have seen, you might be suffering from early memory loss in visual areas. Early memory loss usually begins with inadequate short-term memory, including the recall of a visual display gathered through iconic and visual working memory. If you see something and within a few minutes have forgotten what you have seen, even if you paid close attention, there could be some problems with your short-term memory, as the role of iconic memory is to receive visual input and either transfer it to visual working memory (which then goes on to short-term memory banks) or discard it.
Memory loss is important to catch early, and there are a lot of things you can do to help make the process easier. Contacting a therapist or psychologist is your first step. They can give you a memory test to determine the depth of your memory loss. They can also give you the next steps necessary to identify potential memory loss, and tell you what to watch for if your memory begins to fail.
Frequently Asked Questions (FAQs):
What is iconic memory in psychology?
Iconic memory is a term coined by George Sperling. Sperling identified the process of an entire visual movement from a single, immediate impression via iconic memory, to visual working memory, to short-term memory. These classic initial experiments identified iconic memory as the first threshold in the integration of visual information. Iconic memory, then, is a gateway, of sorts, for the processes involved in storing short-term memory. A visual stimulus offsets the brain, which triggers iconic memory. Iconic memory holds onto the image for 1 second or less, before sending the image to the brain, which quickly identifies whether the image is important or unimportant. Without iconic memory, taking in information and quickly discarding it, the human brain would be continually overwhelmed by visual stimuli. Iconic memory is a sorting machine, essentially, filtering through all of the images taken in on a daily basis.
What is iconic echoic memory?
Iconic memory and echoic memory are actually two different types of memory intake. Iconic memory is involved in eye movements, and entire visual intake, while echoic memory focuses on auditory intake and sorts information based upon auditory receptors. Like iconic memory, echoic memory is short, and does not necessarily route all incoming information immediately to short-term or long-term memory for extended storage.
How long does iconic memory last for?
Iconic memory is incredibly brief, lasting 1 second or less. This is, in part, why change blindness is observed in iconic memory; iconic memory is not used to store a great deal of visual information over a long period of time, so iconic memory is prone to change blindness, or the inability to identify small changes made to a scene. Iconic memory is often linked to visual working memory, which is not as prone to change blindness, and is the part of memory in change detection that can actually last several seconds—long enough to display the ability to detect change.
Why is iconic memory important?
Although iconic memory is known for change blindness and is used in a pre attentive state, it is a vital part of the primary visual cortex and its functions. Through inadvertent or unintentional eye movements, the human mind takes in a veritable cascade of visual information, which must be processed via the primary visual cortex and either discarded or rerouted to the next channels of visual memory. From this primary visual intake center (iconic memory), memories are either deemed no longer necessary and discarded, or shuffled along to the next destination: visual working memory.
A type of memory that struggles with change detection tasks might not seem to be terribly important, but it plays an absolutely essential role in neurological function. Being constantly overwhelmed by visual stimuli could mean a loss of general brain function; if a large portion of the brain was constantly focused on filtering and sorting through visual input, other functions would have to be put on the back burner. Iconic memory takes over these functions, and performs the task of sorting through and removing unnecessary information.
What best describes iconic memory?
Iconic memory is the type of memory involved in the brief and rapid intake of visual stimuli. Iconic memory in change detection is weak, at best, but performs an important function: sorting through and filtering incoming visual stimuli. In the initial studies regarding iconic memory, there were many different tactics researchers used to learn more about the condition, including measuring the intake of visual information through both stimulus onset and stimulus offset. What was discovered is that iconic memory is a rapid visual intake center, which holds onto an image for 1 second or less, before either discarding the image, storing information about the visual stimuli, or sending the image along to longer-term memory centers, such as visual working memory and short-term memory.
Iconic memory is also interesting for its unreliability in recall through visual stimulus alone; studies required participants to view an image with a set of information, then asked them to recall that information from iconic memory. Only ¼ to 1/5 of the given information was able to be retrieved, suggesting that iconic memory was of little use in retaining information. Conversely, when a partial report procedure was produced, and researchers required participants to recall information alongside additional stimuli (most often auditory), they were able to offer a partial report, with as much as 75% of information retained. These studies were fascinating frontiers in human neuroscience, as they provided a window into how sensory integration is used to recall information, as was demonstrated in partial report procedures.
What is iconic memory example?
Iconic memory is the shortest-term visual memory identified in human functioning. Iconic memory includes the brief images taken in by human eyes, which are then discarded or moved along for further processing and storage. While there are many different types of storage that are responsible for processing information, iconic memory is unique, in that it is both brief and rapid: iconic memory stores information for less than one second, and either discards the information, or passes it on to the next step in memory processing. Iconic memory is also known for its ties to partial report procedure, wherein a researcher required participants to view a visual stimulus alongside an additional sensory stimulus, and recall information. Iconic memory cannot provide a complete report (information recall without other sense involvement), but can provide a partial report (information recalled with other sense involvement).
A simple example of iconic memory is this: take a moment to look at an image—for no more than 2-5 seconds—and close your eyes. Can you recall an image of the object you were looking at? The image will likely fade within a single second or less. This is iconic memory. Iconic memory examples within a partial report paradigm include: view an image while chewing a piece of gum. Again, view the image for no longer than 2-5 seconds, before closing your eyes (but continuing to chew the gum). Are you able to more readily recall the image you viewed while chewing gum? If so, you have demonstrated iconic memory within a partial report paradigm.
What's the difference between echoic memory and iconic memory?
Echoic memory is a form of auditory intake and processing, while iconic memory is a form of visual intake and processing. Although they are two separate types of sensory intake and memory processing, there is a situation in which they can be fused: partial report procedure. Partial report procedure can be used to deliver a partial report, or a recollection of visual stimulus alongside auditory stimulus. Perhaps the simplest way to exemplify both iconic and echoic memory in action is to view an image—a painting of a bird, perhaps—while listening to a series of sounds, such as three distinct notes on the piano. Each employs iconic and echoic memory, respectively, but aids each other in effective recall.
Which description of iconic memory is accurate?
The most effective description of iconic memory is a simple one: iconic memory is the first stage in visual intake and processing. Although talk of partial report, complete report, stimulus onset, stimulus offset, and the effects of masking can all convolute and confuse the basic functions of iconic memory, the basis of iconic memory is fairly straightforward: the human brain takes in a great deal of visual stimuli on a moment-to-moment basis, much of it unnecessary to recall. Iconic memory takes in these images—the images of a couch as you walk past, the sight of a fly buzzing in front of you, or the impression of a shadow to the left of you on your walk—and rapidly sorts them either to be discarded as unnecessary information or input, or files them into the next step of visual processing, the visual working memory. From there, images are either discarded or shuffled into short-term memory, where they are once more sorted to either be discarded or sent to long-term memory. If long-term memory is the final destination for a given image, iconic memory is the train ticket purchased to get there.
How can I improve my iconic memory?
Iconic memory is not necessarily an impulse or “muscle” you can “exercise.” Instead, iconic memory is the involuntary initial step in visual processing. Although memory can be strengthened with regular use and intentional practice, iconic memory is not actually a storage site, or a type of memory bank; instead, it is the gatekeeper in visual processing. Images are taken in via iconic memory, routed to the visual cortex, and deemed either unnecessary or worthy of storage. Iconic memory can be used briefly to recall a small amount of information or, when viewed in conjunction with other sensory stimuli, recall a larger amount of information through a partial report paradigm. Partial report allows people to deliver more information, but is still subject to the rapid-fire nature of iconic memory.
Although you cannot quite improve your iconic memory in the same way you might work to improve your short term or long term memory, you can regularly practice partial report procedure to encourage your ability to deliver a partial report. To successfully enlist the partial report paradigm, view a given visual stimulus while engaging another sense, such as listening to a specific song or sound, or chewing on a cracker. When trying to recall the image you are in search of, enlist that same sensory stimulus, and you should be able to deliver a partial report, or a greater portion of the visual stimulus taken in via your iconic memory.