In recent years, there has been a considerable body of research exploring the diagnostic criteria and differing behavioural expressions of autism spectrum disorders (ASDs). Most of this research has been undertaken focusing on males with high functioning autism or Aspergers Syndrome (hereafter referred to as ASD). However, research into the female phenotype has been limited and findings have generally been inconsistent [1–3]. Within this limited literature, it has been suggested that, in order for females to be diagnosed with ASD, they will generally be more impaired than males and frequently have an accompanying intellectual disability [1, 3, 4].
It is generally accepted that, for every female diagnosed with ASD, there are at least four males diagnosed , whereas for those who are also profoundly intellectually disabled the ratio is closer to two males for each female . Among high functioning males and females, there is a common belief that males and females do not differ behaviourally, emotionally or intellectually . However, a fundamental flaw exists in this argument. The supposed gender invariance is not consistent with gender differences evident in the typically developing (TD) population, such as superior social skills observed in females or better friendship stability seen in young males . Furthermore, gender has been shown to impact greatly on many major aspects of development; for instance, through childhood, males demonstrate superior motor skills while female children demonstrate more advanced interpersonal and emotional skills . As such, it seems implausible that gender would not have a significant impact on the expression of ASD. Whether these differences in gender are supported in the ASD population is yet to be examined.
The difficulty in identifying females with ASD may be further compounded by gender differences in sociability, friendships and emotionality in the TD population. That is, social-communicative difficulties are key diagnostic criteria for ASD; yet females with ASD, like TD females, may be less impaired (or demonstrate strengths) in these areas compared to males with ASD . This suggestion, however, has yet to be fully tested. It would appear that the nature of social-communicative and friendship differences among TD females and males very likely impacts differences among males and females with ASD, and it would be useful to assay this empirically, in turn possibly leading to the development of more specific and sensitive diagnostic criteria that have regard to gender. This is critically important as the accurate diagnosis of females with ASD may enhance their access to early and ongoing intervention and support to maximise their development and wellbeing. Findings may also inform specifically tailored intervention programs for females with ASD in a range of areas, including developing and maintaining friendships.
Friendship is widely pronounced to be fundamentally based on three tenants of companionship: intimacy, trust and affection [10–14]. Friendships are integral for developing social supports, essential social skills and gender roles [11, 15, 16]. Intimate friendships among TD males are characterised by rough and tumble play, minimal close connection and a large group of like-minded friends, acquaintances, playmates or strangers [11, 16–19]. TD males are more likely to be inclusive in their networks compared to TD females but are more prone to conflict [12, 20]. In contrast, intimate friendships involving TD females are characterised by sharing and closeness, based on mutual interest, reciprocity and affection. Females also demonstrate greater skills in socio-cognitive functioning compared to males . They tend to have two or three close friends as well as a wider group of friends with whom they regularly interact [16, 20–23]. Interestingly, friendship stability in females tends to be lower than in males , as females are inclined to change friends or terminate friendships more readily than their male counterparts . It is generally accepted that TD females demonstrate superior social skills compared to TD males .
Friendships within the ASD population, however, are characterised somewhat differently. For example, it is well documented that children and adults with ASD regularly report difficulty with associating with peers and maintaining friendships [25, 26]. Using 60 children with ASD, Kasari and colleagues examined social relationships and report that they are more likely to operate on the fringe of their friendship circles and report lower quality of friendships . Children with ASD are reported to be at greater risk of experiencing rejection than TD children. Specifically, the social networks of 44 children with ASD and other disabilities were assessed and the authors concluded that children with ASD are more likely to be rejected than otherwise disabled peers by their TD peers . Reports of feeling abandoned or isolated are not uncommon from children with ASD and this is probably due to their trouble interpreting body language and other social cues . Koning and Magill-Evans  found support for this pattern when they investigated social perception and social networks among 42 boys with and without ASD. Carrington and colleagues  interviewed five children with ASD and established common barriers for children with ASD to develop and maintain friendships. Specifically, they noted that constantly talking about special interests or not wanting to venture outside of comfort zones such as going to new places, or playing a new game are also commonly described as barriers to maintaining friendships for people with ASD [31, 32]. Daniel and Billingsley , based on interviews with seven boys with ASD, report that males with ASD often focus their friendships on mutual interests and activities but noted that, in the absence of these shared interests, the friendships rarely continue. This behaviour is consistent with TD males, whereby males are more likely to socialise around a common interest such as a particular sport or game rather than socio-emotional activities .
Currently, the literature in this area largely focuses on males with ASD, whereby females with ASD are represented by only a few participants in the sample or are excluded altogether . As such, it is difficult to gain a clear understanding of friendships and sociability for females on the autism spectrum. Due to this limitation in the literature, it may be more useful to utilise clinical accounts of the different presentations of females and males with ASD to better understand how these two groups develop and maintain friendships [35–38].
In a clinical description, Attwood  describes females who develop coping mechanisms or an ability to camouflage their social inadequacies through imitating and memorising acceptable social behaviours. This clinical description supports the Camouflage Hypothesis, originally proposed by Wing . Wing proposed that females with ASD develop social skills and coping mechanisms that allow them to blend in or camouflage themselves into society, obscuring a likely diagnosis of ASD, even though there may be other indications of the condition. Specifically, while these skills are not representative of TD females, they may be superior to those characteristically expressed by a male with autism. As such, females on the spectrum still exhibit social deficits compared to TD females, but display relative strengths in this area compared to males on the spectrum. Wing’s hypothesis suggests that females with ASD adapt to and imitate appropriate social skills, allowing them to assimilate into neurotypical social circles. Attwood  reports that clinically he finds females with ASD utilise cognitive skills to respond to social situations. Similarly, Kopp and Gillberg  describe cases of females who clearly demonstrate autistic-like behaviours but did not fully meet criteria for ASD or Aspergers Syndrome, as specified at that time (by the Diagnostic and Statistical Manual of Mental Disorders Third Edition revised). These females are reported to be a diagnostic anomaly whereby their social profile was not at all similar to traditional descriptions of autistic social behaviour .
The under-diagnosis of females with ASD has been examined in three more recent studies. Using autism criteria on the Childhood Autism Spectrum Test, Dworzynski (2012) compared males and females aged between 10 and 12 years who were drawn from more than 15,000 sets of twins in the United Kingdom . When intelligence quotient (IQ) and functioning levels were equivalently high, females were significantly less likely to be diagnosed with an ASD than males. Furthermore, the females displayed fewer socio-communicative symptoms than the males. A similar pattern was reported by Lai and colleagues  with 83 age- and IQ-matched adult males and females with ASD. Specifically, females demonstrated fewer socio-communicative deficits than males and they were less likely to be diagnosed . In contrast to these studies, Carter and colleagues (2007) found no differences between males and females with ASD on measures of social functioning, or on cognitive and developmental functioning. It is important to note that this study was conducted with 100 children (22 females) who had a mean age of 28 months. Comparison of these studies is difficult as their respective age ranges are from babies to adults, thus representing an array of developmental abilities and stages.
Baron-Cohen and Wheelwright  also examined the possibility that females with ASD exhibit social skills which are closer in quality and content to that of TD females than males with ASD. They assessed 27 TD adult males and 49 TD adult females, and compared these to 51 adult males and 17 adult females diagnosed with ASD on the friendship questionnaire (FQ) . As expected, females scored higher on the FQ than males, regardless of diagnosis. Moreover, TD individuals scored higher than those with ASD regardless of gender and no significant differences were found between the males and the females with ASD.
Although these findings are consistent with current clinical observations of gender differences in sociability and emotionality in TD and ASD individuals, caution should be exercised when generalising these findings to the ASD population. The authors did not triangulate their measurements, such as with reports from parents or friends. This is of concern, given the indication that individuals with ASD tend to overestimate the significance of their friendships and relationships . In addition, the age range of the participants in the study was broad (14 to 64 years). Such a large age range poses a number of potential issues. For example, 14-year-olds and 64-year-olds are unlikely to share the same relationship dynamics; their life stage is critical to the development of social skills and friendships . As Baron-Cohen and Wheelwright did not match subjects, differences in ages across the groups would have impacted upon group means on the FQ, possibly enhancing or obscuring group differences in unknown manners. Most importantly, though, differences in ages within each sample would increase error variance of the FQ scores, mathematically rendering a significant result considerably less likely to be obtained. A considerable improvement would be to restrict the age range, for instance to adolescents. In turn, this would provide insight into the social and empathic skills of individuals where these skills are still developing and are most likely to be referred for diagnosis and subsequent intervention. Finally, as with the majority of studies examining ASD, the ratio of male to female participants was not equal. Any heterogeneity of variance across gender therefore renders group differences even more difficult to recognise. Consequently, conclusions made in regard to females with ASD must be taken with caution.
The aim of the present study was to examine the female presentation of ASD by exploring the social aspects of children with ASD. If social and emotional advantages possessed by TD females compared to TD males are in anyway evident in females with ASD, as the evidence above would suggest, differences should be evident in the way females with ASD behave and appear compared to males with ASD. In conjunction with Wing’s Camouflage Hypothesis, it was expected that females with ASD would score differently to males with ASD on Baron-Cohen and Wheelwright’s FQ . More specifically, it was expected that females with ASD would score higher than males with ASD on the FQ. It was also expected that, regardless of diagnosis, female participants would score higher than male participants. As it has been well established that people with ASD experience social deficits, it was also anticipated that TD participants would score higher than ASD participants, regardless of gender.