ic’s InfoSelect lets you “find any data in an instant, no matter where or how you entered it” ( http://miclog.com).

 

figure 1. freemind, a mind map creation tool.

 

Knowledge: A PKB primarily contains knowledge, not information. That is, its purpose is not simply to aggregate all the information sources one has seen, but to preserve the select knowledge that one has learned from those sources. Psychologically, knowledge is the formation of a mental model in one’s own mind that corresponds to the information encountered. 21

Base: A PKB preserves knowledge for the long haul. It is ideally future-proof: immune to shifts in technology and to disaster. It can be fluidly searched and browsed. It also forms a consolidated, integrated whole, without partitions that might isolate some areas of knowledge from others. This is because it is a reflection of one’s own memory, which, as Bush and many others have observed, can freely associate any two thoughts together, without restriction. 3, 9

 

Benefits

What can be gained from using a PKB? An idea of the presumed advantages can be gleaned from the way in which today’s numerous solutions are “pitched:”

Knowledge generation and formulation. Here the emphasis is on procedure, not persistence; it is the act of

figure 2. cmap, a concept map creation tool.

simply using the tool to express one’s knowledge that helps, rather than the ability to retrieve it later. Systems boast that they can “convert random thoughts generated while you are the most creative into the linear thoughts needed most when communicating;” “help you relate and arrange random ideas;” and “stimulate your brain” ( http://mindmappersusa.com).

Knowledge capture. PKBs do not merely allow one to express knowledge, but also to capture it before it elusively disappears. The point is to lower the burden of jotting down one’s thoughts so that neither task nor thought process is interrupted. StayAt-Play’s Idea Knot, for example, asserts that “it is very quick to open a…docu-ment and within seconds record the essence of that new idea without distractions, while your mind is focused on it and without disturbing the flow of your current work.” ( http://www.sta-yatplay.com).

Knowledge organization. A short study on note-taking habits found that “better organization” was the improvement people most desired in their own information recording practices. 24 PKB systems like Aquaminds Notetaker ( http://aquaminds.com) profess to answer this need, allowing one to “organize personal information,” and claiming to be “a more productive way to stay organized.”

Knowledge management and retrieval. Perhaps the most critical aspect of a PKB is that the knowledge it stores is permanent and accessible, ready to be retrieved at any later time. Person-alKnowbase ( http://bitsmithsoft.com) claims it will “give you a place to stash all those stray snips of knowledge where they can be quickly recalled when you need them,” and MicroLog-

PKB systems: Past and Present

A plethora of candidate PKB systems have emerged over the past decades. Here, we give an overview of some of the more notable efforts from three distinct research communities.

Graphical knowledge capture tools. Much fanfare has been generated in the last 30 years around pictorial knowledge representations. Some claim that drawing informal diagrams to represent abstract knowledge is an excellent way to communicate complex ideas, enhance learning, and even to “unlock the potential of the brain.” “Mind mapping” and “concept mapping” are the two most popular paradigms in graphical knowledge capture. A mind map is essentially nothing more than a visual outline, in which a main idea or topic is written in the center of the diagram, and subtopics radiate outward in increasing levels of specificity. The primary value is in the freeform, spatial layout, and the ability for a software application to hide or reveal select levels of detail. The open source Freemind project (see Figure 1) is just one of literally dozens of such tools.

Concept maps34 are based on the premise that newly encountered knowledge must be related to one’s prior knowledge in order to be properly understood. Concept maps help depict such connections graphically (see Figure 2). Like mind maps, they feature evocative words or phrases in boxes connected by lines. However, there are important differences in the underlying data model—tree vs. graph—that will discuss shortly.

Hypertext systems. The hypertext community proudly points to Bush’s article as the cornerstone of their heritage. Hence the development of hypertext techniques, while seldom applied specifically toward PKB solutions, is historically important. Doug Engelbart, who began developing the first viable hypertext system in 1959, stated his purpose as “the augmentation of man’s intellect.” 15 In other words, Engelbart’s goal was to use the hypertext model specifically to model abstract knowledge.