Sample Answer
Section A: How Experimental Investigations of ASD Inform DSM-5 Clinical Features
Introduction
According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5, APA 2013), Autism Spectrum Disorder (ASD) is defined by two core domains: (1) persistent deficits in social communication and social interaction across multiple contexts, and (2) restricted, repetitive patterns of behaviour, interests, or activities. These features may include difficulties in social reciprocity, nonverbal communication, and relationship development, alongside repetitive movements, inflexible routines, or fixated interests. Experimental research in cognitive neuroscience, developmental psychology, and neuroimaging has played a critical role in validating these clinical observations. This essay evaluates how empirical findings from experimental studies support and refine the DSM-5’s conceptualisation of ASD.
Social Communication Deficits: Eye-Gaze Studies
Point: Experimental eye-tracking studies have provided direct evidence for the social attention deficits central to DSM-5 criteria.
Evidence: Jones and Klin (2013) found that infants later diagnosed with ASD showed declining attention to others’ eyes between 2 and 6 months of age, while typically developing infants maintained high gaze fixation.
Explanation: This experimental finding indicates that atypical social attention begins early, supporting the DSM-5 description of “persistent deficits in social-emotional reciprocity.”
Link: Thus, eye-tracking research reinforces the DSM-5’s emphasis on early-emerging social interaction difficulties as a core diagnostic feature.
Impairment in Joint Attention
Point: Deficits in joint attention, a key early social skill, are consistently found in experimental research.
Evidence: Mundy et al. (2009) demonstrated through behavioural tasks that children with ASD struggle to initiate or respond to joint attention cues such as pointing or gaze-following.
Explanation: These deficits disrupt shared understanding and social learning, directly linking to DSM-5’s criteria for deficits in developing and maintaining relationships.
Link: Experimental evidence of joint-attention impairment thus validates the DSM-5’s inclusion of nonverbal communication difficulties in ASD diagnosis.
Language and Communication Processing
Point: Experimental investigations into language comprehension show neural atypicalities consistent with DSM-5 communication criteria.
Evidence: Kuhl (2017) used ERP (event-related potentials) and found that children with ASD exhibit reduced neural discrimination for phonemes in speech.
Explanation: This suggests underlying auditory and linguistic processing deficits that explain the pragmatic communication issues described in DSM-5.
Link: The DSM-5’s categorisation of ASD as involving social communication deficits aligns closely with this experimental evidence.
Restricted and Repetitive Behaviours
Point: Cognitive-experimental studies have linked repetitive behaviours to reduced cognitive flexibility.
Evidence: Ozonoff et al. (2004) employed executive-function tasks like the Wisconsin Card Sorting Test and found that children with ASD performed significantly worse, showing rigid thinking patterns.
Explanation: This demonstrates that repetitive or ritualistic behaviours stem from executive dysfunction rather than simple habit.
Link: DSM-5’s focus on restricted and repetitive behaviours is strongly supported by such experimental evidence.
