Hyperarousal to sensory input among those with Autism (Belmonte and Yurgelan-Todd, 2003 Hirstein et al, 2001; Tordjman et al, 1997) accompanied by an impairment to choose between competing stimuli is widely observed. EEG studies involving tasks requiring people with Autism to selectively attend to relevant stimuli and ignore irrelevant stimuli have shown either an abnormal heightened P1 evoked potential to the relevant stimuli or an abnormally generalized response to irrelevant stimuli (Townsend and Courchesne, 1994). Additionally, the N2 to novel stimuli is heightened in children with Autism, even when these stimuli are irrelevant to the task (Kemner et al, 1994). Similar results have been seen using auditory stimuli (Kemner et al, 1995). This supports behavioral observations that children with Autism can either be overly focused on one aspect of a task or greatly distracted by stimuli irrelevant or peripheral to the task. During tasks requiring shifts of attention between hemifields, those with Autism have been shown to exhibit both hemispheres activating indiscriminately instead of the usual hemispheric-specific patterns of activation (Belmonte, 2000). Physiological measures suggest that perceptual filtering in Autism occurs in an all-or-nothing manner with little specificity in selecting the location of the stimulus, for the behavioral-relevance of the stimulus or even the sensory modality in which the stimulus occurs (Belmonte, 2000). It has been suggested that this tendency for hyperarousal to sensory input must result from some pervasive underlying abnormality in neural processing rather than one specific brain locus (Belmonte et al, 2004; Johnson et al, 2002; Akshoomoff et al, 2002). Some authors suggest this neuronal dysfunction to be low signal-to-noise ratio developing from abnormal neural connectivity (Bauman and Kemper, 1994; Raymond et al, 1996; Casanova and Buxhoeveden, 2002; Belmote et al, 2004).
The result of this type of processing is that all stimuli are given equal priority by the autistic brain causing an overwhelming flood of sensory information to be handled. The typical brain is able to identify and ignore irrelevant stimuli and focus valuable attention on that which is task-relevant creating a much more efficient processing system. The autistic brain, on the other hand, takes it all in and then must actively discard irrelevant information at a later processing stage causing, in effect, a processing bottleneck (Belmonte, 2004). Functional neuroimaging studies show that the brains of those with Autism tend to show increased activation in areas that rely on primary sensory processing and decreased activity in areas typically supporting higher-order processing (Ring et al, 1999; Critchley et al, 2000; Schultz et al, 2000; Pierce et al, 2001; Baron-Cohen et al, 1999; Castelii et al, 2002).
It has been proposed that this low-level processing disruption underlies the higher-level abnormalities exhibited in Autism (Belmonte, 2004) and that the widely observed symptomology of Autism (including issues of Theory of Mind and executive function) is an emergent property of abnormal neural growth (Akshoomoff, 2002). There is molecular evidence that this abnormality is present at birth (Nelson et al, 2001) even though obvious behavioral symptoms often do not typically arise until 18-24 months. A child born reliant on this over-aroused, under-selective sensory processing is open to a flood of stimuli that is thought to overload the newly emerging higher-order cognitive processes (Belmonte and Yurgelun-Todd, 2003). When faced with this processing constraint, the developing and plastic brain is forced to re-organize to accommodate that constraint (Johnson et al, 2002). This is manifested in the abnormal organization of the autistic brain as described above and the cognitive style characteristic of Autism that relies heavily on lower-order, local feature processing at the expense of higher-order, global information processing known as weak central coherence (Happe, 1999; Frith and Happe, 1994).
Central coherence describes the ability to process incoming information in context, pulling information together for higher-level meaning, often at the expense of memory for detail (Happe, 1999). Weak central coherence then is the tendency of those with Autism to rely on local feature processing (the details) rather than taking in the global nature of the situation. Kanner (1943) saw, as a universal feature of Autism, the “inability to experience wholes without full attention to the constituent parts.” It is this cognitive style that makes people with Autism superior at resisting visual illusions (Happe, 1999), have a higher occurrence of absolute pitch (Heaton et al, 1998), excel at the Embedded Figures Task (Shah and Frith, 1983; Jolliffe and Baron-Cohen, 1997) and possess the ability to copy “impossible” figures (Mottron et al, 2000).
These neurophysiological and neuroanatomical studies paint a picture of the world occupied by those with Autism as chaotic, overwhelming and filled with “noise”. Coupled with this is an internal environment of hyperarousal (Hirstein, 2001; Cohen and Johnson, 1977; Hutt and Hutt, 1979; Hutt et al, 1965; Kootz and Cohen, 1981; Kootz et al, 1982). This is corroborated by autobiographical reports from some people with Autism (Bluestone, 2002; Williams, 1994; Gillingham, 1995; Jones et al, 2003). Considering this fragmented, chaotic and overwhelming world implies then that a child’s external environment is a key and primary factor to be considered when designing a treatment program for children with Autism. Physical environments with higher amounts of sensory stimulation (e.g bright visual displays, background noise, etc.) will add to the “noise” in an already overloaded sensory system, making any new learning extremely challenging. While there is acknowledgment that children with special needs do require specifically designed environments (Carbone, 2001; Reiber and McLaaughlin, 2004; Schilling and Schwartz, 2004), the extent to which rooms can be tailored to meet the needs of these children is highly constrained by a typical classroom setting, mainly due to the presence of other children and the subsequent size of the room––even something as ubiquitous as fluorescent lighting has been shown to affect the behavior of children with Autism (Colman et al, 1976). These environmental considerations are often overlooked and their importance underestimated.
The SRP bypasses the constraint of the classroom by employing a room (usually in the child’s home) that is specifically designed to lower sensory stimulation. Only neutral colors are used and distracting patterns or highly contrasting colors are avoided. There are no distracting visual displays or noises and only incandescent or natural lighting is employed. All toys and objects are kept off the floor on wall-mounted shelves to provide a distraction-free floor area for play. Most importantly, play sessions in the playroom usually include one adult and one child. This means that the child does not have to try and filter out the noise and movement of other children but deals only with a predictable adult whom s/he trusts. The SRP holds that these simple measures aid in soothing the autistic child’s over-active nervous system by making the world digestible and manageable. There is evidence for a sub-set of children with Autism who do not exhibit an overactive autonomic system but instead display unusually low levels of arousal (Hirstien et al, 2001). These are the children who tend to engage in “extreme” activities (e.g. climbing very high, constantly moving, etc.) in order to “kick-start” their arousal levels. The SRP playroom provides a safe and contained environment in which to do these activities, many of which are not feasible in a typical classroom.
It can be seen that this treatment principle of SRP is supported by the current neuroanatomical and physiological data. Direct investigation of the effects on children with Autism of the SRP playroom in contrast with traditional classrooms has not yet been undertaken. Children in home-based Son-Rise Programs® often instigate going into the playroom, will play in there even when they are alone and talk about how much they enjoy their special room. There is much anecdotal evidence supporting this claim but to date, no study has looked at either qualitative measures of children’s perceptions of their playrooms or quantitative physiological measures of nervous system activity of children with Autism in these environments.Next Page