Toddler interventions for ASD are often delivered in a naturalistic and interactive social context (e.g. play). It typically involves child-directed teaching strategies (e.g. child-preferred materials). Naturalistic developmental behavioural interventions (NDBI) refer to interventions that employ a naturalistic and interactive social context and involve child-directed teaching strategies.

Learning is facilitated by an affective exchange between the child and the therapist. However, children with autism have deficits in affective sharing and social motivation. This thus needs to be promoted for children with autism for interventions to be effective.

NDBIs make use of a constructivist approach where children’s learning experiences are designed to actively engage attention (1), help them connect new experiences with existing knowledge (2), teach within developmental sequences (3) and systematically increase the complexity of learning experiences (4). Child initiative and spontaneity are fostered and rewarded. Everyday routines are a rich learning context for children and interventions within these contexts allows for adaptive functioning in natural contexts and environments.

Varying teaching stimuli (1), alternative prompting strategies (2), use of child-preferred activities (3), use of incidental teaching strategies (4) and consideration of developmental prerequisites (5) increase children’s motivation and performance. It makes use of more natural rewards (1), reinforcement of attempts (2) and treatment delivery in a more naturalistic and developmentally sensitive context (3).

Generalization of newly learned skills is better when these skills are taught in naturalistic contexts for children with autism. Using naturalistic contexts for interventions when children are still very young has the following benefits:

• It leads to a reduced dependence on prompts.
• It leads to more natural-sounding language.
• It makes learning language meaning more efficient.
• It leads to habituation to everyday distractions present in the real-world.

There are several core components of NDBI interventions:

1. Nature of the learning targets (i.e. build strong learning infrastructure)
   The intervention targets often include the entire range of developmental domains and it emphasizes the integration of knowledge and skills across developmental domains and promote generalization of newly learned skills at every phase of the intervention. Skills are taught to be integrated with other skills and are not taught in isolation. NDBI attempts to provide the child with an infrastructure to support efficient and effective learning. Intervention targets focus on developing knowledge and abilities that can enhance developmental achievements (e.g. joint attention; imitation).
2. Nature of the learning contexts
   The context of learning need to allow children to experience the natural contingencies of their own behaviour. Learning is improved when it is embedded in activities that contain emotionally meaningful social interactions. In NDBIs, this is done by establishing adult-child engagement activities that transform into motivating play routines or familiar daily life routines.
3. Nature of development-enhancing strategies
   This includes motivating strategies, behavioural strategies (e.g. modelling) and joint activities. This is believed to lead to better outcomes and the strategies need to be very rewarding.

There are several common features of NDBIs:

1. Three part contingency
   All NDBIs utilize a three part contingency (i.e. ABA; antecedent-response-consequence).
2. Manualized practice
   All NDBIs have clear procedures which are described in their manuals. This allows for consistency of treatment and helps with training.
3. Fidelity of implementation criteria
   All NDBIs has fidelity of implementation (i.e. the degree to which a treatment is implemented as it is supposed to be). This is done to ensure the integrity of treatment implementation.
4. Individualized treatment goals
   All NDBIs have some form of goal development that is individualized to the child.
5. Ongoing measurement of progress
   All NDBIs have some form of ongoing measurement of progress.
6. Child-initiated teaching episodes
   All NDBIs use a strategy which involves the presentation of an instruction or opportunity to respond within the context of a child-chosen of child-preferred activity or familiar routine. The child thus selects an activity and in that activity, a teaching opportunity is presented. This may increase child motivation.
7. Environmental arrangement
   All NDBIs use a set of techniques which involves setting up the environment so that the child must initiate or interact with the adult to obtain a desired outcome (e.g. receive a toy).
8. Natural reinforcement and related methods for enhancing child motivation
   All NDBIs use some form of natural reinforcement to enhance child motivation and reinforce attempts of the child (i.e. loose shaping; reinforcing attempts). Another technique to enhance child motivation includes interspersing easier and more difficult tasks. Varying the degree of complexity to targeted skills may help to keep the children’s language and play interactions more natural.
9. Use of prompting and prompt fading (i.. scaffolding)
   All NDBIs use some form of prompting and prompt fading. This includes inserting a cue between the instruction and the target behaviour to elicit a desired response and create the context for delivering the reinforcer. The goal of prompting is to support behaviours currently outside of the child’s repertoire or not yet under control so they can occur and be reinforced.
10. Balanced turns within object or social play routines (i.e. turn-taking)
    All NDBIs use some form of turn-taking to increase social reciprocity, maintenance of interactions and turn-taking with materials. It also creates opportunities for the therapist to control access to the materials.
11. Modelling
    All NDBIs use some form of modelling to teach target skills and is used as a specific prompt strategy (i.e. thus requiring imitation).
12. Adult imitation of the child’s language, play or body movements (i.e. contingent imitation)
    All NDBIs use some form of reciprocal imitation (i.e. contingent imitation) and this is used to increase the child’s responsivity and attention to adult (1), imitation of the adult (2) and continuation of the interaction (3).
13. Broadening the attentional focus of the child
    All NDBIs aim to broaden the attentional focus of a child by, for example, teaching with multiple and varied stimuli.

Children with autism are typically characterized by overselectivity. This refers to the phenomenon wherein the child’s behaviour comes under the control of a range of stimuli that is too limited or irrelevant (e.g. only recognizing a person by their glasses).

Guidelines for treatment with children with ASD include parent education (1), starting as early as possible (2) and blending behavioural and developmental strategies to address core issues (3). A parent coaching component accelerates developmental progress in ASD.

Future studies need to improve on NDBIs in six ways:

1. Have an increased emphasis on larger scale and more contemporary RCT designs that can address moderators and mediators and efficiency of treatment.
2. Include measurement of intervention outcomes that represent meaningful change.
3. Have an empirical analysis of the active ingredients within multicomponent interventions.
4. Understand the necessary procedural fidelity of individual components within treatments and treatment packages.
5. Develop new methodological approaches to test treatment strategies for improving the outcomes of NDBIs.
6. Utilize innovative methods to implement and sustain research-based NDBIs in the context of community programmes.