ATTENTION & MEMORY ASPECTS OF APD
Children who display symptoms of APD may also have weaknesses in important cognitive processing systems that enhance audition. Problems in the critical abilities of attention and memory will directly interfere with auditory perception. If a child cannot hold an auditory image in his/her initial echoic (perceptual) memory the child will not transfer the correct information to his/her short term (working) memory. Inability to transfer images into or out of short term memory will leave a child unable to organize memories of speech sounds or to develop sound equivalents to alphabet letters (certainly important for reading and writing skills). During day to day discussions and school lessons the child with weaknesses in auditory short term memory will have enormous stress attempting to keep up with the ongoing stream of speech from teachers and 'specials'. As a result the child may frequently miss key elements of assignments and/or have difficulty following two or three stage directions. Importantly, learning in general is more difficult for children with APD because they are unable to keep up with new information that streams by them as it is presented by the teacher . Thus, each day the material is new. For the other children in the classroom, those without APD, the material has been 'heard' before, thus it is more familiar.
Attention is another immensely important aspect of APD. Sound is an incredibly brief signal. If I say, "hello," the word is immediately gone once I have said it. If a child is not 'listening' when someone says hello the child does not 'hear' it. On the contrary, look back two lines and read the word 'hello'. You can do it because, unless erased, written images persist. Tactile images persist. We even enjoy, after dinner, lingering tastes of what we ate for dinner. We can also recognize when someone has been smoking in a room we have entered because of the persistent smoke odor. Sound, however, is gone as quickly as it occurs. Hence, if a child is not 'attending' to a particular speaker at a specific moment he/she will most likely 'miss' part of what the speaker has said. The result will be gaps and inconsistencies in the child's perception of what was said. To really understand the impact of attention on audition one must understand that, like memory, there are multiple aspects (or types) of attention. Briefly, attention encompasses a variety of functions. There is initial 'focus' or 'recognition' attention. It scans the environment and recognizes every possible auditory image. If a particular stimulus is more important or attractive to the listener 'selective attention' is brought into play. This is 'sustaining' attention or 'maintenance'. This aspect of attention retains possession of the mind and keeps the subject's orientation toward the interesting stimulus. Another attention is that of 'vigilance'. If a child is listening for the teacher to announce homework, amidst everything else the teacher is discussing the child is 'keying' on the word homework. As the stream of spoken speech races by, the child must be able to quickly recognize and attend to that portion which he/she has been vigilant toward (or listening for). Weak auditory vigilance causes a child to be less involved with the world because he/she is unable to grab that which has been deemed important out of the ongoing speech. Attention 'switching' is yet another form of attention. It is the ability to divert one's attention from one item to another and then effectively jump back to that same point that was left. Some children do well attending to one stimulus or task, but have trouble switching back and forth from one task to another. When they attempt this switching they become lost and have trouble picking up at the appropriate spot each time. Another child may have difficulty with 'spare' attention. This relates to load and capacity. The child may perform well at one level of attention, but as task demands increase the child does not have enough attention 'reserve' (spare attention) to pull from in order to continue with effective maintenance.
These additional processing abilities (memory and attention) can greatly influence how a child's auditory system scans, focuses on, grasps and integrates auditory stimuli. As an aside, this is partially why many people claim to have difficulty distinguishing between APD and ADD. Children with impulsive-type ADD are inattentive to all sensory stimuli. They have more opportunities to evaluate signals that are visual or tactile (more permanent images as compared to brief auditory signals that are fleeting and transient), thus in these children we are more likely to observe weaknesses that appear to be auditory-based. It is important to remember that APD is a disorder that relates to sound input and listening. Whereas, children with ADD experience difficulties in many more sensory areas than do children who experience APD.