In this interesting paper, Conway and colleagues discuss
the effect of hearing impairment on the perception of non-auditory sequences.
They argue that because auditory stimuli always occur over time and always have
a sequential aspect, we learn to represent sequences or events that unfold over
time through the auditory modality.
In any task that requires the perception, learning, or
memory of a sequence, people perform best when the stimulus is auditory rather
than visual or tactile. For example, adults perceive and reproduce sequences of
sounds more accurately than sequences of flashes. People perform better on
short-term memory tasks when the stimuli are auditory, such as spoken words,
than when the stimuli are visual, such as pictures of objects or even written
words.
How was this tested? Conway and colleagues had three groups
of participants listen to auditory sequences, watch visual sequences, or feel
tactile sequences through stimulation of different fingers. After each pair of
sequences, the participants were asked to decide whether the sequences were
identical or different from one another. All the stimuli in these sequences
were non-linguistic. The participants did not know that the sequences had been
constructed according to certain “grammar” rules. For example, sound number 1
always came after sound number 2 or number 3, but not after sound number 4.
In the second stage of the experiment, the participants
were told that the sequences had been constructed according to certain rules.
They were then asked to listen to, watch, or feel new sequences, some of which
were constructed according to the same rules as the sequences in the first part
of the experiment, and some of which were not. The participants were asked to
decide, for each sequence they experienced, whether it was constructed
according to the same rules as in the first part of the experiment or not. It turned out that the participants who had listened to
the sequences in the first part performed twice as well on the classification
task as the participants who had watched or felt the sequences in the first
part. Thus, the ability to learn rules, such as grammatical rules or arithmetic
rules, is based on auditory processing.
Therefore, hearing loss at an
early stage of development creates a cascade of effects that changes cognitive
and perceptual abilities, not only auditory processing. Hearing loss will
mainly affect cognitive abilities related to learning, retrieving, and performing
sequential information. People with hearing impairment show difficulties in
non-auditory functions related to time and sequence, including immediate memory
for sequences.
Conway and colleagues examined sequencing skills in two
groups of children aged 5–10: children with hearing impairment and a cochlear
implant, and children of the same age without hearing impairment. The children
completed tests of motor sequence processing and production from the NEPSY
assessment. In one task, they were asked to repeatedly tap the thumb and index
finger together as quickly as possible. In another task, they were asked to
touch the thumb to each of the fingers in sequence, from the index finger to
the little finger, in order, as quickly as possible. It turned out that the
hearing-impaired children performed worse on these tasks than the children in
the control group and also worse than the test norms. The same hearing-impaired
children did succeed on other tasks that did not involve sequence processing,
such as visuospatial memory and tactile perception.
In another experiment, the same groups of children watched
sequences of colored squares displayed on a screen, were asked to remember the
sequences, and then tapped the colored squares on the screen in the same
sequence. During both parts of the experiment, the children did not know that
the sequences had been constructed according to certain “grammar” rules,
similarly to the previous experiment described above. In the second part of the
experiment, the children were shown new sequences produced by the same rules,
as well as new sequences that were not produced by those rules. The researchers
examined how well the children learned the two types of new sequences. The children with normal hearing learned the new
sequences that had been constructed according to the same rules as in the first
part of the experiment much better than the new sequences that had not been
constructed according to those rules. In contrast, the children with hearing
impairment learned both types of sequences to the same extent. In other words,
the children with normal hearing learned the grammatical rules from which the
sequences in the first part, and some of the sequences in the second part, had
been constructed better than the children with hearing impairment. This happened despite the fact that all the sequences
were presented visually.
These experiments show that
children with hearing impairment have more difficulty learning motor sequences
and visual sequences than children with normal hearing. Thus, hearing
impairments may lead to delays in learning sequences that are not necessarily
auditory. These difficulties in sequence learning may make it harder, beyond
the hearing difficulties themselves, to learn the grammatical rules of spoken
language, to learn rules in arithmetic, and to learn any type of procedure.
Conway, C. M., Pisoni, D. B., & Kronenberger, W. G. (2009). The importance of sound for cognitive sequencing abilities: The auditory scaffolding hypothesis. Current Directions in Psychological Science, 18(5), 275–279. https://doi.org/10.1111/j.1467-8721.2009.01651.x
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