What are the advantages and disadvantages of forward and backward chaining?
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haining is a way to teach a multi-step or complex skill. While often used as a component of ABA instruction, chaining can be used to teach anyone a complex skill. A complex skill is a skill that really consists of several small behaviors that are linked or chained together, to accomplish a terminal goal. An example of a skill consisting of several discrete behaviors is wiping a table.
Show Teaching a skill using chaining is commonly recommended if the child can only perform some of the steps, consistently misses/skips steps, or is completing steps incorrectly. For example, on a daily basis the child throws their wet toothbrush in the sink instead of putting it in the toothbrush holder. That would be a good situation to introduce chaining into. Another issue I see commonly is the child who independently uses the bathroom, and then consistently fails to button/zip their pants back up. That is a child who could benefit from a chaining program. A way I like to explain chaining is by comparing it to cooking. I am a recipe person. Even if I have made something multiple times, I still like to have the recipe in front of me. Imagine I asked you to make me some oatmeal raisin cookies, but I gave you no recipe to follow and no expectations of exactly what to do. What kind of raisins do I like? Do I like cinnamon in my cookies or vanilla extract? Do I prefer chewy or crisp cookies? You would likely start or finish the cooking chain successfully, but have errors or missed steps in the middle. This is why using chaining to teach a skill can be so helpful. For a child with Autism, hearing a demand like “make your bed” may not mean anything. They may need a recipe to follow, which clearly states my expectations of how to complete the task. The 3 types of chaining are: Backward chaining, Forward chaining, and Total Task chaining. Backward Chaining- Backward chaining refers to teaching a behavioral chain beginning with the last step: you would completely prompt the entire chain of behaviors except the last step. Using the tooth brushing example, the child would be prompted to do every single step and then would independently put the toothbrush in the toothbrush holder. Backward chaining is recommended if the child can successfully complete more steps at the end of the behavior chain. Backward chaining also has the advantage of creating a link between the most work and the biggest reinforcer. If I am using backward chaining to teach a child to make French toast, then I would prompt every step and have the child independently use a spatula to move the toast from the pan to a plate. Then we get to eat! So the most work (independent step) led to the biggest reinforcement (consuming the food). Once the last step is mastered at an independent level, then move to the last 2 steps, then the last 3 steps, etc. Forward chaining- Forward chaining refers to teaching a behavioral chain beginning with the first step: have the child complete the first step independently and then prompt all remaining steps. Using the tooth brushing example, the child would independently pick up their toothbrush out of the toothbrush holder, and then all remaining steps are prompted. Forward chaining is recommended if the child can successfully complete more steps at the start of the behavior chain. Forward chaining has the advantage of using behavior momentum, as the 1st step is often the simplest, easiest step. If I am using forward chaining to teach a child to make French toast, then I would have the child get the bread out of the refrigerator independently, and prompt every other step. Once the first step is mastered at an independent level, then move to the first 2 steps, then the first 3 steps, etc. Total task chaining- As the name implies, total task chaining is when you teach the complete behavior chain one step after another. Total task is what most teachers or parents naturally use to teach a skill. E.g. "Okay turn the water on...now soap up your hands....good, now scrub your hands together", etc. The adult walks the child through each step, prompting as necessary. For a child with Autism, this may still be too complex of a teaching style. For that reason, backward or forward chaining is usually more commonly used for kiddos with Autism. Backward and forward chaining are methods of reasoning that exist in the Expert System Domain of artificial intelligence. These techniques are used in expert systems such as MYCIN and DENDRAL to generate solutions to real life problems. This article provides an overview of these techniques, and how they work. By the end of the article, readers will have learned real life examples of how backward and forward chaining are applied in artificial intelligence. A brief overview of an expert system can help us gain more insights on the origin of backward and forward chaining in artificial intelligence. An expert system is a computer application that uses rules, approaches, and facts to provide solutions to complex problems. Examples of expert systems include MYCIN and DENDRAL. MYCIN uses the backward chaining technique to diagnose bacterial infections. DENDRAL employs forward chaining to establish the structure of chemicals. There are three components in an expert system: user interface, inference engine, and knowledge base. The user interface enables users of the system to interact with the expert system. High-quality and domain-specific knowledge is stored in the knowledge base. Backward and forward chaining stem from the inference engine component. This is a component in which logical rules are applied to the knowledge base to get new information or make a decision. The backward and forward chaining techniques are used by the inference engine as strategies for proposing solutions or deducing information in the expert system.  Image Source: Tutorials Point Forward chainingForward chaining is a method of reasoning in artificial intelligence in which inference rules are applied to existing data to extract additional data until an endpoint (goal) is achieved. In this type of chaining, the inference engine starts by evaluating existing facts, derivations, and conditions before deducing new information. An endpoint (goal) is achieved through the manipulation of knowledge that exists in the knowledge base. Image Source: Tutorials Point Forward chaining can be used in planning, monitoring, controling, and interpreting applications. Properties of forward chaining
Examples of forward chainingA simple example of forward chaining can be explained in the following sequence. A A->B B A is the starting point. A->B represents a fact. This fact is used to achieve a decision B. A practical example will go as follows; Tom is running (A) If a person is running, he will sweat (A->B) Therefore, Tom is sweating. (B) A DENDRAL expert system is a good example of how forward chaining is used in artificial intelligence. DENDRAL is used in the prediction of the molecular structure of substances. Deducing the chemical structure starts by finding the number of atoms in every molecule. The mass spectrum of the sample is then used to establish the arrangement of the atoms. We can summarize these steps as follows. The chemical formula is determined ( the number of atoms in every molecule). The spectrum machine is used to form mass spectrums of the sample. The isomer and structure of the chemical are identified. In this example, the identification of the chemical structure is the endpoint. In the DENDRAL expert system, a generate and test technique is employed. There are two elements in the generator: a synthesiser and structural enumerator. The synthesiser plays the role of producing the mass spectrum. The structural enumerator identifies the structure of substances and prevents redundancy in the generator. Advantages
Disadvantages
Backward chainingBackward chaining is a concept in artificial intelligence that involves backtracking from the endpoint or goal to steps that led to the endpoint. This type of chaining starts from the goal and moves backward to comprehend the steps that were taken to attain this goal. The backtracking process can also enable a person establish logical steps that can be used to find other important solutions. Image Source: Quora Backward chaining can be used in debugging, diagnostics, and prescription applications. Properties of backward chaining
Example of backward chainingThe information provided in the previous example (forward chaining) can be used to provide a simple explanation of backward chaining. Backward chaining can be explained in the following sequence. B A->B A B is the goal or endpoint, that is used as the starting point for backward tracking. A is the initial state. A->B is a fact that must be asserted to arrive at the endpoint B. A practical example of backward chaining will go as follows: Tom is sweating (B). If a person is running, he will sweat (A->B). Tom is running (A). The MYCIN expert system is a real life example of how backward chaining works. This is a system that’s used in the diagnosis of bacterial infections. It also recommends suitable treatments for this type of infections. The knowledge base of a MYCIN comprises many antecedent-consequent rules, that enable the system to recognize various causes of (bacterial) infections. This system is suitable for patients who have a bacterial infection, but don’t know the specific infection. The system will gather information relating to symptoms and history of the patient. It will then analyze this information to establish the bacterial infection. A suitable sequence can be as follows: The patient has a bacterial infection. The patient is vomiting. He/she is also experiencing diarrhea and severe stomach upset. Therefore, the patient has typhoid (salmonella bacterial infection). The MYCIN expert system uses the information collected from the patient to recommend suitable treatment. The recommended treatment corresponds to the identified bacterial infection. In the case above, the system may recommend the use of ciprofloxacin. Advantages
Disadvantages
ConclusionBackward and forward chaining are important methods of reasoning in artificial intelligence. These concepts differ mainly in terms of approach, strategy, technique, speed, and operational direction. Forward chaining is important to developers that want to use data-driven algorithms to develop effective computer-based systems. Backward chaining is important to developers that are interested in using goal-driven algorithms to design effective solutions in complex database systems. What are the advantages of backward chaining?Although it is unclear if backward chaining is more effective than other chaining procedures, one advantage of backward chaining is that the terminal reinforcer is always delivered as the individual completes each step.
What advantage does backward chaining have over forward chaining?Forward chaining can be used for tasks such as planning, design process monitoring, diagnosis, and classification, whereas backward chaining can be used for classification and diagnosis tasks. Forward chaining can be like an exhaustive search, whereas backward chaining tries to avoid the unnecessary path of reasoning.
What is forward chaining and backward chaining?Forward chaining is known as data-driven technique because we reaches to the goal using the available data. Backward chaining is known as goal-driven technique because we start from the goal and reaches the initial state in order to extract the facts.
Is forward or backward chaining better?Forward chaining is recommended if the child can successfully complete more steps at the start of the behavior chain. Forward chaining has the advantage of using behavior momentum, as the 1st step is often the simplest, easiest step.
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