Echoic memory

Echoic Memory, the auditory version of sensory memory, refers to the phenomenon in which there is a brief mental echo that continues to sound after auditory stimuli has been heard. In comparison to sensory and iconic memory, echoic memory is thought to last a little longer, for upwards of about three or four seconds. Due to its short span, echoic memory is a type of short term memory as the echoic memories are temporal and last only for a brief period of time. A simple example of working echoic memory is having a friend recite a list of numbers, and then suddenly stopping, asking you to repeat the last four numbers. To try to find the answer to the question, you have to “replay” the numbers back to yourself in your mind as you heard them. Since Echoic memory lasts for a few seconds, if there was no pause between the time your friend stopped reciting the list to the time where he asked you to repeat the last digits, then your echoic memory would be able to pick up the last few numbers and recite them back quite accurately. However, if there was a pause between the time he stopped counting to the time he asked you to repeat the numbers, your recall would not be as high because the numbers have left your echoic memory (Brown, 2001). Echoic memory has been studied in patients that suffer from schizophrenia. When given two different sound tones, schizophrenic patients were unable to match two tones after a very short delay time (300 milliseconds) but were able to correctly match when there was no delay between the tones. This showed that schizophrenia affects the brain regions which control echoic memory outside the prefrontal cortex (Strous et al., 1995).

Echoic memory can be expanded if it is repeated in the phonological loop which rehearses verbal information in order to keep it in short term memory. In this case, if your friend was giving you his phone number, you would be mentally repeating it to yourself, a sort of “inner voice.” Then, if he stopped reciting the numbers and asked for you to recite them back, there would be a more probable chance that you could correctly recite all the numbers, despite if there was a slight pause or not (Bogen, 2006).

Experimental Evidence
In studies conducted by N. Cowan, he noted that there is evidence that echoic memory is involved in auditory attention, as well as finding evidence for two separate systems (Cowan 1984), which strengthened Baddeley’s proposal, and his model of working memory (Baddeley 1978). This idea was then expanded by Ben Weedon and Zofia Kaminska who studied echoic memory’s role in auditory attention and found that echoic memory can play a significant role in models of auditory attention after noting that attentional capacity was 3 auditory streams when echoic memory was able to contribute to memory performance (Weedon & Kaminska, 1999).