Research has found that blind children have better short-term memory than sighted children

According to the American Psychological Association (2020), memory can be defined as “The ability to retain information or a representation of past experience, based on the mental processes of learning or encoding, retention across some interval of time, and retrieval or reactivation of the memory.” This broad definition encompasses the several types of memory that are recognized by the field of neuropsychology: The short-term memory, the working memory, and the long-term memory. Each of these memories are activated in our daily lives, either consciously or unconsciously. Examples include brushing one’s teeth, buttoning a shirt, reading a text, or listening to a friend describing a sequence of events that occurred during the day.

Working memory is often referred to as the human “post-it” because it allows us to temporarily store two types of information: The phonological or speech-based information, and the visual information (Braddeley, 1986, 2000). Working memory becomes useful for encoding information while simultaneously processing other information, for example, when taking notes in class. Short-term memory, on the other hand, involves situations that require a person to store or hold information for a short period of time without necessarily manipulating it or performing a task, for example, recalling a phone number immediately after it was recited. Finally, long-term memory is the act of storing information for an extended period of time, for example, remembering how to drive a car. Depending on the type of memory at hand, different processes are usually involved. Those processes can either be perceptual or verbal. One question arises: Does blindness affect memory functions?

In an attempt to answer this question, Swanson and Luxenberg conducted a study in 2009, comparing children with congenital blindness to children with sight on tasks that require short-term memory and working memory, in order to compare their performance when it comes to recalling information. For the first experiment, the researchers recruited 17 blind children from public, private, and center schools for the blind, and matched them with 19 sighted students from private and public schools. Matching was made on the basis of age (10-13 years old), gender, socioeconomic status, and verbal IQ scores. In their study, they defined blindness as “minimal light or movement perception but no shape perception” which is due to a variety of factors such as retinopathy of prematurity, macular degeneration, or cancer. Several short-term and working memory tests were administered to the participants, with short-term tasks including repeating sentences, repeating unrelated words in a specific order, or repeating a set of digits both forward and backward. As for the working memory tasks, these include holding or storing complex information while responding to a question or performing a task, recalling street addresses, organizing sequences of words into categories, or retelling series of episodes.

The same 17 children with blindness participated in the second experiment, but a different group of 25 sighted children were recruited from a private school. Participants were first asked to recall words that are phonemically similar, in other words asking them to rhyme words. Participants were also asked to listen to sentences and recall the last word of each sentence. For both experiments, results indicate that the blind children performed better on short-term memory tasks but not on working memory tasks. One way to explain the results is that loss of vision forces an individual to rely on more intact processes, in this case, auditory monitoring and speech discrimination. These results go hand-in-hand with other findings that suggest that blind children perform better than sighted children in auditory discrimination tasks (Röder et al., 1996), and complex language processing tasks. Studies have also shown that both short-term and long-term memory is enhanced in people with blindness (Röder & Rösler, 2003).

In conclusion, the literature tends to support the idea that blind individuals have a phonological acuity and perform better on short-term memory tasks compared to sighted children. From a neuropsychological point of view, this study confirms the idea that short-term memory and working memory are distinguishable constructs, as the terms are often used interchangeably. From a more humane point of view, this study provides input on cognitive abilities in people with blindness. More specifically, it shows that while these people are visually impaired, they seem to be cognitively skilled and excel on phonological tasks that focus on sound and language.

A disability, or a gift ?

References

American Psychological Association (2020). https://dictionary.apa.org/memory

Baddeley, A. D. (1986). Working memory. London: Oxford University Press.

Baddeley, A. (2000). The episodic buffer: A new component of working memory? Trends in Cognitive Sciences, 4, 417–423

Röder, B., & Rösler, F. (2003). Memory for environmental sounds in sighted, congenitally blind and late blind adults: Evidence for cross-modal compensation. International Journal of Psychophysiology, 50, 27–39.

Röder, B., Rösler, F., Hennighausen, E., & Nacker, F. (1996). Event-related potentials during auditory and somatosensory discrimination in sighted and blind human subjects. Cognitive Brain Research, 4, 77–93.

Swanson, H. L., & Luxenberg, D. (2009). Short-Term Memory and Working Memory in Children with Blindness: Support for a Domain General or Domain Specific System? Child Neuropsychology, 15(3), 280-294. https://doi.org/10.1080/09297040802524206