Iconic and Echoic Memory: Definitions and Examples

Most people are familiar with the concept of "memory" as the ability to recall events that happened previously. Sensory memory allows individuals to retain impressions of sensory information for a brief time after the original stimulus has ceased.

Sensory memory, or sensory register, is a brief collection of information from your senses. This includes your hearing, touch, smell, taste and vision. Your sensory memory gathers information at the highest resolution - it’s taking a quick, detailed picture of your environment. Then, it sends that information to your short-term memory. You can’t regulate how long these memories last, but they usually only stay for a couple of seconds. This helps you better understand small nuances about your environment.

Sensory memory is an automatic response considered to be outside of cognitive control. It allows individuals to remember great sensory detail about a complex stimulus immediately following its presentation. Information from sensory memory has the shortest retention time, ranging from mere milliseconds to five seconds. It is retained just long enough for it to be transferred to short-term (working) memory.

According to the Atkinson-Shiffrin theory of memory, memory is comprised of three major components: sensory, short-term, and long-term. Echoic memory is a type of sensory memory. As the name implies, sensory memory involves detecting and maintaining sensory information for potential use.

Your five senses make up the types of sensory memory including:

• Echoic memory: Hearing
• Haptic memory: Touch
• Gustatory memory: Taste
• Iconic memory: Vision
• Olfactory memory: Smell

Examples of sensory memory include:

• Echoic memory: The melody of your favorite song continuing even after the song finished playing
• Haptic memory: Continuing to feel the grasp after someone lets go of your hand
• Gustatory memory: The taste of dinner remaining after you’ve finished your meal
• Iconic memory: Seeing the color of fireworks after they’ve faded
• Olfactory memory: Continuing to smell bread after walking out of a bakery

Sensory memory functions in the following way:

1. You experience a sense.
2. The area of your brain responsible for that sense (sensory cortex) briefly activates. It happens very quickly, like pressing a button.
3. You focus your attention on only the important pieces of information gathered.
4. You move those pieces to your short-term memory.

Your sensory memory only holds information for about 0.2 to 2 seconds. This can vary based on which sense you experience. For example, iconic memory (vision) typically lasts for 1 second.

Sensory memory has a large capacity. This is because you often use multiple senses at the same time.

For example, you may use all five senses when you’re eating a meal. You see the food. You feel the texture on your tongue. You smell the different ingredients. You hear the crunch when you chew. And you taste it. Your sensory memory can take in information from all of those senses as they happen.

While sensory memory has a large capacity, it only lasts for a few seconds before either moving to another memory storage area of your brain or disappearing so you can experience other senses.

There are many different parts of your brain involved in sensory memory. Each sense follows a pathway.

Let’s say you hear a sound. This sound converts into an electrical signal that nerve fibers carry into your brain. It first passes through your brainstem and then up through your thalamus (the middle of your brain). Your thalamus directs the signal to the correct area specific to the sense.Sensory Memory: How Our Brains Process Information

Iconic Memory

Iconic memory is sensory memory from visual input. Iconic memory, or visual sensory memory, holds visual information. It’s a type of sensory memory, just like echoic memory. Iconic memory is sensory memory from visual input.

But iconic memory is much shorter. It lasts for less than half a second.

That’s because images and sounds are processed in different ways. Since most visual information doesn’t immediately disappear, you can repeatedly view an image. Plus, when you look at something, you can process all the visual images together.

Echoic Memory

Echoic memory is sensory memory based on auditory (sound) input. What is echoic memory? Echoic memory is sensory memory from auditory (sound) input. Echoic memory is the brief sensory memory of audible sounds. Echoic memory is one type of sensory memory process.

Specifically, echoic memory is sensory memory associated with auditory information received from the environment. The term echoic stems from the word echo, which is in reference to the brief echo, or the reverberation of sound that is transmitted neurologically via this type of sensory memory.

Echoic memory allows the brain to retain spoken syllables in order for the brain to process them into intelligible speech. Music and conversation are immediately processed by echoic memory to allow the brain to interpret words and their meaning. An echoic memory example is seen in conversation. Echoic memory allows the recall of words that were spoken when not listening. Echoic memory occurs automatically whether a person consciously tries to remember what they've heard.

Echoic memory is processed in the left hemisphere of the brain. The left hemisphere of the brain primarily processes echoic memory. The brain processes auditory information from echoic memory in the primary auditory cortex (PAC). The PAC of the left ear stores sounds heard with the right ear and vice versa. Sounds heard with both ears are stored in bilateral PACs.

Your echoic memory stores audio information (sound). It’s a type of sensory memory along with iconic (visual) and haptic (touch-based).

Echoic memory is a subcategory of human memory, which can be divided into three major categories:

• Long-term memory retains events, facts, and skills. It can last for hours to decades.
• Short-term memory stores information you recently received. It lasts for a few seconds to 1 minute.
• Sensory memory, also called the sensory register, holds information from the senses.

It can be further broken down into three types:

• Iconic memory, or visual sensory memory, handles visual information.
• Haptic memory retains information from your sense of touch.
• Echoic memory holds audio information from your sense of hearing.

The purpose of echoic memory is to store audio information as the brain processes the sound. It also holds bits of audio information, which gives meaning to the overall sound.

When you hear something, your auditory nerve sends the sound to your brain. It does this by transmitting electrical signals. At this point, the sound is “raw” and unprocessed audio information.

Echoic memory occurs when this information is received and held by the brain. Specifically, it’s stored in the primary auditory cortex (PAC), which is found in both hemispheres of the brain.

The information is held in the PAC opposite of the ear that heard the sound. For instance, if you hear a sound in your right ear, the left PAC will hold the memory. But if you hear a sound through both ears, both the left and right PAC will retain the information.

After a few seconds, the echoic memory moves into your short-term memory. This is where your brain processes the information and gives meaning to the sound.

The process of echoic memory is automatic. This means audio information enters your echoic memory even if you don’t purposely try to listen.

In fact, your mind is constantly forming echoic memories. Here are a few everyday examples:

• Talking to another person. Spoken language is a common example. When someone talks, your echoic memory retains each individual syllable. Your brain recognizes words by connecting each syllable to the previous one. Each word is also stored in echoic memory, which allows your brain to understand a full sentence.
• Listening to music. Your brain uses echoic memory when you listen to music. It briefly recalls the previous note and connects it to the next one. As a result, your brain recognizes the notes as a song. An echoic memory example is demonstrated with music. Notes played on a piano are stored in echoic memory long enough for the brain to process the notes into a recognizable song or melody. Echoic memory allows the brain to interpret individual notes into a recognizable song.
• Asking someone to repeat themselves. When someone talks to you while you’re busy, you might not fully hear what they say. If they repeat what they said, it will sound familiar because your echoic memory heard them the first time. When someone is distracted and asks a friend, "What did you say?" Echoic memory is the reason that they immediately recognize the words even when they weren't actively listening to the conversation. The person's echoic memory retained the words even though it was not done consciously.

This brief duration means your brain can make many echoic memories throughout the day. All humans have echoic memory. However, various factors can influence how well someone has this type of memory.

Possible factors include:

• age
• neurological disorders, such as Alzheimer’s disease
• psychiatric disorders, such as schizophrenia
• substance use
• hearing loss or impairment
• language disorders

It also depends on the characteristics of a sound, including:

• duration
• frequency
• intensity
• volume
• language (with spoken word)

How Long Does Echoic Memory Last?

Echoic memory lasts three to four seconds before the information disappears. Echoic memory lasts for 2 to 4 seconds before your brain can process the sound. While echoic memory is very short, it helps keep information in your brain even after the sound has ended.

If someone wishes to remember the brief burst of information in their echoic memory, they must consciously transfer the auditory information into their short-term memory. Long-term memory allows someone to recall a melody or recognize bird songs that were heard years ago.

Echoic memory is longer, which is useful because sound waves are time sensitive. They can’t be reviewed unless the actual sound is repeated. Also, sound is processed by individual bits of information. Each bit gives meaning to the previous bit, which then gives meaning to the sound. As a result, the brain needs more time to store audio information.

A German American psychologist by the name of Ulric Neisser defined the concept of echoic memory in 1967. Not long after Sperling's research on iconic memory, cognitive psychologist Ulric Neisser popularized the term echoic memory, referencing the auditory equivalent of what Sperling had discovered in the realm of visual sensory memory. Since the work of Sperling and Neisser, echoic memory has been studied extensively around the world by cognitive psychologists. The work of men like Sperling and Neisser has contributed greatly to the development of the knowledge base on sensory and echoic memory that we possess today.

Memory Models

A variety of different memory models have been proposed to account for different types of recall. In order to explain the recall process, however, a memory model must identify how an encoded memory can reside in memory storage for a prolonged period of time until the memory is accessed again, during the recall process.

The multi-trace distributed memory model suggests that the memories being encoded are converted to vectors (lists of values), with each value or “feature” in the vector representing a different attribute of the item to be encoded. These vectors are called memory traces. A single memory is distributed to multiple attributes so that each attribute represents one aspect of the memory being encoded.

These vectors are then added into the memory array or matrix (a list of vectors). In order to retrieve the memory for the recall process, one must cue the memory matrix with a specific probe. The multi-trace model has two key limitations: the notion of an ever-growing matrix within human memory sounds implausible, and the idea of computational searches for specific memories among millions of traces that would be present within the memory matrix sounds far beyond the scope of the human-recalling process.

The neural network model assumes that neurons form a complex network with other neurons, forming a highly interconnected network; each neuron is characterized by the activation value (how much energy it takes to activate that neuron), and the connection between two neurons is characterized by the weight value (how strong the connection between those neurons is).

The dual-store memory search model, now referred to as the search-of-associative-memory (SAM) model, remains one of the most influential computational models of memory. Two types of memory storage, short-term store and long-term store, are utilized in the SAM model.

In the recall process, items residing in the short-term memory store will be recalled first, followed by items residing in the long-term store, where the probability of being recalled is proportional to the strength of the association present within the long-term store.

Spreading activation is a theory proposed that relates storage of memories to the activation of a series of nodes. These nodes create an activation pattern of other related nodes and this is how singular events are remembered.

Memory testing in both iconic and echoic memory defined the difference between whole and partial reporting. When testing echoic memory, someone is given a series of spoken letters or numbers. They are less able to give a whole report and recall all of the spoken letters. If asked to recall a specific portion of the spoken letters, the partial recall is much higher and accurate. Partial reporting surpasses accuracy when compared to the whole reporting.

That’s because images and sounds are processed in different ways.

We all forget things sometimes. It’s also normal to experience some memory loss as we get older. But if you’re having serious memory issues, it’s important to see a doctor.

Seek medical help if you have memory problems, such as:

• getting lost in familiar places
• forgetting how to say common words
• repeatedly asking questions
• taking longer to do familiar activities
• forgetting names of friends and family

Depending on your specific issues, a doctor might refer you to a specialist, like a psychologist or neurologist.

Though we all have echoic memory, factors like age and neurological disorders can affect how well you recall sounds. It’s also normal for memory to decline with age. Learn what echoic memory is and see an echoic memory example. An echoic memory example is seen in conversation.