Memory
Episodic memory is defined by the ability to recall the specific perceptual and spatio-temporal context surrounding an event. For example, it is common to have the experience of meeting someone that you know you have seen before but cannot remember where from. Later on, you might suddenly be able to remember the context in which you first saw this person. This memory for additional contextual information is what defines episodic memory, which is highly important for day-to-day functioning, social interaction, and self-identity. Episodic memory in autism has been increasingly researched over the past few years and studies have uncovered subtle differences in the way information is remembered. For example, autobiographical-episodic memories, which are memories for events in our own personal past, have been shown to be less detailed and specific in individuals with autism and take longer to retrieve, suggesting that memory for specific details of past events is more difficult to recall. In contrast, memory for item-specific information, not tied to a particular spatio-temporal context, has been shown to be typical or even superior in individuals with autism. While there appears to be a specific difficulty in recollecting information in autism, it is currently unclear exactly why this occurs. Our previous research aimed to dissociate theories of episodic memory differences between individuals with autism and typically developed individuals and to explore whether specific encoding or retrieval mechanisms can account for these differences, on both behavioural and neurological levels.
Audition
Individuals with ASD commonly report an increased awareness of environmental sounds, abnormal loudness perception, and difficulty in filtering or hearing out the important auditory information in background noise. This can cause significant speech-recognition difficulties in settings such as classrooms and school halls where background noise can be very high. We have investigated the speech communication abilities of individuals with ASD by asking them to listen to sentences presented in different types of background noise, to assess speech in noise perception. Individuals with ASD were found to be significantly poorer at identifying key words in the sentences than the control participants, especially for background noises that contained variations in amplitude over time modulations (i.e., temporal "dips")(Alcántara et al., 2004). Additionally, frequency selectivity refers to our ability to separate the frequency components in a complex sound, and to improve the speech-to-noise ratio (SNR). We have shown that frequency selectivity abilities in autism are no different to those of neurotypical individuals (Alcántara et al., 2012). This is important because it rules out the possibility that the auditory difficulties in autism are simply due low-level hearing loss in the cochlear and therefore directs us to consider other hearing processes.
Language
Individuals with autism show a range of linguistic difficulties, across the entire IQ range. Several studies have examined the use of sentence context in spoken language and have suggested that individuals with autism have difficulty using context to resolve ambiguous linguistic information (Brock, Norbury and Nation, 2008). Seminal work by Happé (1997) demonstrated that autistic children make more errors by selecting the incorrect pronunciation of homographs than typical controls, regardless of contextual cues (e.g. "a tear in a dress", tear rhyming with deer). Consequently, it has been suggested that individuals with autism are unable to integrate linguistic information. However, we have explored other explanations for these results. For example, in the case of the homographs, individuals with autism may find the common pronunciation so salient that they cannot inhibit it as they read the sentence out loud. Alternatively, people with autism may have difficulty accessing the rare pronunciation of the homographs under the time pressures of the experiment. Furthermore, uncontrolled confounds in homograph tasks used previously may have underestimated true levels of contextual processing in autism (Brock 2013).
Sensorimotor processing in autism
Movement is our main pathway to interacting with the world around us and the output of our motor system ranges from hard-wired reflexes to complex, multilimb goal-directed actions. The exact neural mechanisms that control the integration of motor control and sensory processing are still unknown and the extent of this problem is most apparent in robotics where functional bipedal robots are still very difficult to manufacture. Differences in motor control and movement are reported for as much as 80% of individuals with autism (Green, 2009) and yet their etiology and relationship with the core symptoms of autism remains relatively unexplored. This is surprising as motor development and cognitive development have been shown to be interrelated in the typical population, both in terms of neural functioning (Diamond, 2000) and behavioural outcome (Steele et al., 2010). Although the literature on differences in motor cognition and motor control in ASD is divided (Gilbert et al., 1990; Ozonoff, 2008), it has been suggested that motor disturbances might be a cardinal feature of ASD (Fournier et al., 2010) and deviances are typically reported to be observable in the earliest stages of life (Teitelbaum et al., 1998; Baranek, 1999; Provost, Lopez & Heimerl, 2007). Our previous research focussed on how people predict movements and the sensory feedback they receive as a consequence of their own actions and whether these predictions of future sensory input might be processed differently in people with an autism spectrum disorder. Differences in how previous experiences and contextual information are used to guide movements and sensory processing might be one way of explaining the sensory differences that are often observed in and reported by individuals on the autism spectrum.
Neurodiversity
CLaRA alumni were interested in the communication between individuals with autism spectrum disorders and professionals who investigate autism and how this affects the research that is conducted. Previous surveys have shown that many people on the autism spectrum are unhappy with the way autism is researched or even feel left out and ignored by professionals. They wanted to know more about the underlying dynamics that cause this apparent ‘rift’ between researchers and individuals with autism and if it is as deep as has been suggested. They asked asking professionals who work in the field of autism research as well as individuals with a diagnosis on the autism spectrum to fill in a short questionnaire. We hope to ensure a close link between CLaRA and the autism community in all our research projects. If you would like to be involved in this, please join our ConnectA database.