Bottom-Up and Top-Down Strategies (or Processing): What Are They Anyway?

A colleague of mine recently asked me to explain the difference between bottom-up and top-down reading strategies. I feel a need to add the interactive approach to reading to these descriptions, as well. 

Essentially, bottom-up, top-down, and interactive approaches to reading are the theoretical models used to describe how print is processed. Each are described below.

Bottom-up strategies (or bottom-up processing): Bottom-up strategies incorporate the lower-level reading processes that teach students to construct meaning from the most basic units of language, including letters, letter clusters, and words. Students make meaning of a text by building on a foundation of analyzing the smallest units of meaning. 

Bottom-up reading strategies begin with letter-sound correspondences (the bottom) to achieve comprehension (the top). Bottom-up processing begins with letters and sounds, building to morpheme and word recognition, and then gradually moving to grammatical structure identification, sentences, and longer texts. A phonics approach to teaching reading supports bottom-up processes. Phonics is a method to facilitate students' access to text to ultimately lead to comprehension.

Top-down strategies (or processing): Top-down strategies instruction focuses on activities that construct meaning rather than on mastering bottom-up skills. Students generate meaning by employing background knowledge, making predictions, and searching the text to to confirm or reject the predictions that are made. 

According to supporters of this approach, comprehension resides in the reader. The reader uses background knowledge, expectations, assumptions, and questions and engages in pre-reading strategies, such as previewing the text, predicting, and activating background knowledge. 

Interactive approach:The interactive approach is considered the most comprehensive description of the reading process. The best readers use an interactive reading approach. An interactive approach to reading combines elements of both bottom-up and top-down reading processes simultaneously. For example, a reader may begin reading a text using top-down strategies to comprehend the text, and then shift to bottom-up strategies when he or she encounters an unfamiliar word. The reader then uses bottom-up strategies to decode the new word before moving on. 

Another way to illustrate the interactive approach to reading is as follows: Recognition of letters (bottom-up processes) leads to recognition of words, which leads to comprehension (bottom to top). Conversely, context, inferences, and world knowledge (top-down processes) can influence lower-level processing strategies, affecting readers' expectations about words and meanings and thus helping readers recognize words faster (top to bottom).