When we walk down a street, we may see many faces, but we ignore almost all of them. Unless we are purposefully looking for someone, only the occasional face will impinge on our consciousness. Similarly, a creaky floor or a nearby railroad crossing where the train whistle blows at 2 AM may annoy us when we first move into an apartment or house, but our mind soon learns to ignore these sounds and lets us sleep. These are examples of our perception filter at work. Our perception filter operates in all realms of our consciousness. It plays an important part in what and how our students learn and should play a central role in what and how we teach. This may be obvious, but having a visual model of a perception filter can guide the way we think about education.
For me, the most satisfying definitions of science acknowledge the generation and testing of models of how the natural world behaves. Often in the molecular life sciences, models are diagrams of mental images that represent real objects and relationships we infer but cannot see. Like cartoons, they capture essential components and ignore others. A model's utility lies in its ability to predict and explain observable phenomena.
As I transitioned from being primarily a research scientist to being primarily a science educator, I was introduced to other models that would have helped me as a teacher, if I had been aware of them. Among them are the Perry Model that describes the intellectual and ethical development of college students , Bloom's taxonomy that provides a hierarchy of cognitive ability , and classification of personality types that helps understand how people interact . Models in education tend to be more textual, like concept maps, with lines connecting ideas.
Recently, at a process-oriented guided inquiry learning (POGIL) workshop, I was introduced to an information processing model [4, 5] that captured my attention (penetrated my perception filter). Although I had seen its component ideas in words before, the presentation of these ideas and their relationships as a diagram allowed me to visualize a perception filter as shown below. Unlike molecules depicted in biochemical models, a perception filter is an abstraction. There is no physical entity in the brain that we can call the perception filter. Yet, the idea, presented as a picture, makes sense to me.
When I scan the table of contents of a journal, most of the titles fly by without a second look while I stop at others, reread the title, and maybe go on to read the abstract and article. Why? I presume there is something in the title that connects with prior knowledge in my long-term memory that has generated the perception filter. It is as if my mind were looking specifically to build on things it already knew. Some call it scaffolding. Once I am looking at the abstract, I am engaged. The material has slipped through my perception filter, and it is being processed and is available to add to or alter my long-term memory.
Perception filters are important. I don't want to read every article in a journal. However, when it comes to education where we as teachers are the table of contents and we don't get past students' perception filters, there is a problem. Although some skillful orators manage to captivate an audience, few teachers have that ability. Unless the listener processes the incoming information in their working memory, preferably with interaction with other people, it may not get transferred to long-term memory. Hence the common instructor remark after an examination, “I covered that, but they didn't get it,” as if it were only the students' fault.1
Since being introduced to the visual imagery of a perception filter developed by Johnstone [4, 5], I have shared it with faculty colleagues and my students. The imagery works for them as well. I assert that the objective of active-learning strategies like problem-based learning or POGIL is to generate situations and activities that open holes in the perception filter and allow information to invade the student's working memory space. There they can address misconceptions accessed from long-term memory or store new information that has been processed more deeply.