Written July 21, 2009

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What do "Coherence" and "Cohesion" Mean?

The two words, "coherence" and "cohesion" mean different things but the two ideas are connected and, in fact, overlap. "Coherence" in an essay (or when you are speaking about interconnected idea in the Speaking test) means the overall "understandability" of what you write or say. When writing an essay, coherence involves such features as: summarizing the overall argument of an essay in the introductory paragraph; presenting ideas in a logical sequence; putting separate, major points into separate paragraphs; and beginning each paragraph with a 'topic sentence', following by supporting sentences. Coherence is based more on the logic of the ideas and how they are presented rather than on the language that is used to express these ideas.

"Cohesion" refers to the degree to which sentences (or even different parts of one sentence) are connected so that the flow of ideas is easy to follow. To achieve good cohesion, you need to know how to use "cohesive devices", which are certain words or phrases that serve the purpose of connecting two statements, usually by referring back to what you have previously written or said. For example, if you write "Statement A" and then follow with the words, "On the other hand, Statement B", then these two sentences "cohere" or "stick together" and it is easy to follow the flow of ideas. Good cohesion leads to good coherence, which is the ultimate aim.

Here's an example of how coherence and cohesion overlap. If you have a major new point to add to your essay then you should put that in a paragraph by itself and begin the paragraph with a topic sentence that more or less summarizes the point you want to make. This topic sentence, following by supporting sentences, make your paragraph more coherent. However, your essay will be less coherent if you suddenly start a paragraph without some form of connection to what you have previously written, either in the previous paragraph or some other previous part of your essay. This problem can be overcome by beginning that topic sentence with words such as, "On the other hand", which connect to the last statement made in the previous paragraph. This shows good cohesion.

For both Task 1 and Task 2 of the Writing test, "Coherence and Cohesion" is one of the four items that is given a sub-score. The other three items are: Task Response (or, Task Achievement for Task 1), Lexical Resource ( = vocabulary) and Grammatical Range and Accuracy.