04/27/2011 01:24 pm ET Updated Nov 17, 2011

Is Implicit Learning Impaired in People with Autism?

In the spirit of autism awareness month, I'd like to emphasize that autism is on a spectrum, and, like every other kind of mind, includes both disadvantages and advantages in daily life. Unfortunately, there are a lot of unfounded assumptions regarding the deficits of people with an autism spectrum disorder. One big one is that people with autism have difficulty with implicit learning. But is it true?

Implicit Learning in Autism

What is implicit learning? Most of the learning that takes place outside the classroom environment is done implicitly -- no explicit instruction is available or necessary. The general consensus in cognitive science is that implicit learning involves "learning that proceeds from practice with any structured environment, in the absence of an intention to learn, and results in knowledge that improved performance even when it is difficult to verbalize"

On first blush, it may seem as though individuals with an autism spectrum condition (ASC), who are typically characterized by social, communicative and motor impairments, would have deficits in implicit learning mechanisms, which would cause such overt impairments. Overcoming some prior limitations of earlier studies, I conducted a study with a team of researchers led by Jamie Brown at the Laboratory for Research into Autism at the University of Cambridge to see whether this is true.

We compared the performance of 26 children with high-functioning autism spectrum condition to 26 typically developing children on four implicit learning tasks, each one designed to tap into a different domain of implicit learning. We even administered a measure of implicit social learning that researchers have assumed would show an impairment in people with autism. We minimized reliance on explicit strategies. We matched the two groups on IQ. We administered a measure of explicit learning for comparison purposes and we administered a reliable index of autistic symptomatology that relates to real-world implicit learning performance. (See "Can People with Autism Learn Implicitly?" for a more detailed summary of the methods and results of our study.)

We found no difference in implicit learning ability between the autism spectrum condition group and the typically developing control group. This lack of a difference between the groups was not a consequence of compensation by explicit learning ability or IQ; in fact we found there was a difference between the two groups in explicit learning, but not implicit learning. Finally, we found no relationship between implicit learning ability in the laboratory and real-world autism spectrum condition symptomatology. Our conclusion: whatever is causing the social, communicative or motor impairments found in those with autism spectrum condition, it is not implicit learning.

Fast forward to a more recent study at the University of Szeged that replicates and extends our findings. Whereas our study administered implicit learning tasks all together at one point in time, Dezso Nemeth and his colleagues looked at the effect of a 16-hour delay on learning a difficult implicit learning task. Their task was constructed in such a way as to allow them to differentiate between general skill (overall speed of learning) and sequence-specific learning (speed of learning the specific implicit pattern).

Thirteen children with autistic spectrum disorder were compared with 13 IQ-matched and 14 age-matched children. Because they also were interested in the effects of consolidation, the children went through two testing sessions: a learning phase and then a testing phase 16 hours later.

They found that children with autism spectrum condition demonstrated similar levels of general skill learning and implicit learning compared with the two control groups, one matched in IQ and the other matched in age. Strikingly, the groups did not differ from one another in consolidation over a 16-hour period! There were also no differences among the groups in forgetting the implicit pattern, and there were no differences among the groups in offline improvements in general skill.

In our paper, we argued that our findings overcame prior study limitations by administering an implicit learning task that minimizes explicit strategies. It looks like the Nemeth and colleagues study, also using a complex regularity that minimizes explicit strategies, discovered similar findings.

Taken together, these studies suggest that individuals with autism spectrum disorder can learn implicitly just as well as typically developing individuals, over short and longer periods of time. They also suggest that processes other than implicit learning disrupt the operations of otherwise intact implicit learning mechanisms of individuals with ASC, having a negative impact on the development of these skills. Of course, the million-dollar question now is this: what are some of these potential processes?

We can think of a few possibilities. One possibility is that real-world implicit learning impairments may result from the tendency for ASC individuals to use explicit strategies to learn about their world. In short: they tend to overthink things. This overuse of explicit strategies by ASC individuals may interfere with the capacity to learn language, social and motor skills implicitly. Indeed, there is evidence that for implicit acquisition to proceed normally, the learning must not be obstructed by explicit strategies.

Another possibility is that the implicit learning mechanisms of people with autism are intact but are simply not directed at the same things as in typical individuals. This could occur as a result of well-established differences in ASC attention. For example, from a very early age, autistic individuals tend to attend to mouths more than eyes. This kind of attentional difference could certainly cause a difference in what is learned implicitly, even when fundamental mechanisms are equivalent. In line with this explanation, autistic individuals have been found to possess considerable skill at distinguishing different pictures of mouths but relative deficits in distinguishing different pictures of eyes. For instance, one study found enhanced performance in people with ASC on a task involving mouth expertise, an area of the face to which ASC individuals typically allocate an unusual amount of attention.

A third possible explanation is that the implicit learning mechanisms are intact in people with ASC, but the knowledge derived from implicit learning is not applied successfully. This could explain why in the laboratory people with ASC may display intact implicit learning but not be able to apply their learning in real-world situations. This possibility would be consistent with other research on the split between ability and application in ASC and would be in line with "a recent shift toward understanding ASC in the context of dysfunctions in introspection or self-referential processing."

Almost all learning, and especially school learning, involves a mix of explicit and implicit cognitive processes. Helping individuals with an autism spectrum disorder access their implicitly learned material while minimizing focusing on their explicit knowledge may aid real-life learning in those with an autism spectrum condition. As we noted in our paper, a potential source of difficulty for those with autism is their over-reliance on explicit strategies. As Nemeth and his colleagues note, "Using these results, therapists can design more effective educational and rehabilitation programs. Our findings suggest that learning mechanisms associated with frontal-striatal-cerebellar anatomy are partly intact in ASD."

I hope this research will show how important it is for researchers to properly test stereotypes about people. It turns out that not only can people with autism learn implicitly, but they do so superbly.