International guest lecturer: Lillian Pelios from Athens visits IAA

On Monday 13 April, we had the pleasure of welcoming Lillian Pelios as a guest lecturer at IAA’s weekly in-house training session. Lillian holds a PhD in psychology and is a faculty member at The American College of Greece in Athens, where she teaches applied behavior analysis — and she runs an ABA centre in the city. She generously shared both her professional story and her clinical thinking with the whole IAA team.

From first steps to running a centre

Lillian walked us through her journey into behaviour analysis: her early exposure to the field, her academic training, the workplaces that shaped her clinical approach, and the process of establishing and operating her own centre. For those of us in the room who know what it takes to build and sustain a specialised ABA service, there was a lot to recognise — and a lot to compare notes on.

Early and intensive intervention — with Lovaas as the methodological foundation

The clinical centrepiece of the session was early and intensive training of children with neurodevelopmental disorders, using the Lovaas curriculum as the primary methodological framework. The Lovaas model — formally known as Early Intensive Behavioural Intervention (EIBI) — has one of the strongest evidence bases in the field. Lovaas’s landmark 1987 study demonstrated that children receiving 40 hours per week of intensive behavioral treatment showed substantial gains in IQ, language, and adaptive behaviour, with nearly half achieving functioning in the typical range by age seven. These findings have been replicated by independent research groups on multiple occasions, and the model remains one of the most thoroughly studied approaches to early autism intervention available.

What distinguished Lillian’s presentation was not just the curriculum itself, but the way her centre structures the progression of training across settings.

From 1:1 to dyad to group — a systematic progression

Lillian described a training structure that begins with intensive 1:1 work and moves gradually through dyad settings, small groups, and eventually larger groups. This is not simply a matter of convenience or resource management. Each step in the progression deliberately increases the complexity of the learning environment — more people, more simultaneous stimuli, less predictability, and fewer opportunities for the therapist to control every variable.

A child who reliably demonstrates a skill in a 1:1 setting may not demonstrate it when two other children are present. That gap is not a failure — it is clinical information. It tells us exactly what still needs to be taught.

This matters because skills like sustained attention, tolerance for distraction, and behavioural flexibility are not simply prerequisites to learning — they are themselves targets that must be systematically trained, in parallel with content-specific skills such as listener responding, matching, intraverbals, mands, and the foundational academic and daily living skills that form the core of a comprehensive curriculum. Group settings reveal gaps in these supporting skills that a 1:1 context simply cannot expose.

Generalisation — the ability to use a skill across different people, settings, and contexts — is one of the seven core dimensions of applied behaviour analysis, and one of the most clinically demanding to achieve. Research consistently shows that for children with autism and related neurodevelopmental disorders, generalisation does not emerge automatically from skill acquisition. It must be followed up intentionally, with systematic variation in the conditions under which skills are taught and practised. As Stokes and Baer argued in their foundational 1977 paper, generalisation is not a passive by-product of learning — it is an active target that requires its own technology. The structured progression Lillian described is one practical and principled approach to building that variation in from the start, rather than treating it as an afterthought once a skill has been acquired in the clinic.

ABA in Greece — a different context, familiar challenges

Lillian also spoke about the situation for behaviour analysis in Greece. The field faces significant resistance there — arguably more so than in Norway — and families who want ABA-based services for their children largely bear the costs themselves, with limited or no public funding. The result is that even families who recognise the value of intensive intervention often receive only a few hours per week, simply because that is what they can afford.

It was a reminder of how much the conditions for good clinical work depend on the system around it — and of how many families in many countries are still navigating largely on their own.

Lillian brought both clinical depth and a great deal of warmth to the session. The discussion it sparked — about methodology, about what we take for granted in our own practice, and about what we might sharpen — was exactly the kind of exchange that makes these internundervisning sessions valuable.

We are grateful to Lillian for travelling from Athens to spend time with us, and we look forward to staying in touch with the broader international ABA community she is part of.

Lovaas, O. I. (1987). Behavioral treatment and normal educational and intellectual functioning in young autistic children. *Journal of Consulting and Clinical Psychology, 55*(1), 3–9.

McEachin, J. J., Smith, T., & Lovaas, O. I. (1993). Long-term outcome for children with autism who received early intensive behavioral treatment. *American Journal on Mental Retardation, 97*(4), 359–372.

Sallows, G. O., & Graupner, T. D. (2005). Intensive behavioral treatment for children with autism: Four-year outcome and predictors. *American Journal on Mental Retardation, 110*(6), 417–438.

Stokes, T. F., & Baer, D. M. (1977). An implicit technology of generalization. *Journal of Applied Behavior Analysis, 10*(2), 349–367.

Baer, D. M., Wolf, M. M., & Risley, T. R. (1968). Some current dimensions of applied behavior analysis. *Journal of Applied Behavior Analysis, 1*(1), 91–97.

Reichow, B., & Wolery, M. (2009). Comprehensive synthesis of early intervention behavioral interventions for young children with autism based on the UCLA Young Autism Project model. *Journal of Autism and Developmental Disorders, 39*(1), 23–41.