Limitations of human mind

Why do we care about them?

Manifests of a limited human mind

How fast can we make a decision?

The Hick-Hyman Law of decision making: T=a*log(n+1) for n equally possible choices. The logarithm suggests a tree representation of choices when we evaluate them. +1 because of uncertainty about whether to respond


How fast can we move our hand?

Fitts' Law: T=a+b*log(1+D/W)

One can derive Steering Law from Fitts' Law

Rate of Communication with machines and humans

How fast can we type?

Words per minute: 33 wpm for transcription by average computer users; 50 to 80 for professional typists

How fast can we read?

college students can raud (read with comprehension) at a typical rate of 300 wpm. (Source: R.P. Carver, Reading Rate: A Review of Research and Theory. Academic Press, 1990.)

How fast can we speak?

Audiobooks: 150-160 wpm.

How many words can we speak in a day? This leads to a fundamental limit to our communication bandwidth with peers and the size of an effective team.

When adding staff to a project, ask what exactly is the bottleneck: communication or dirty, textbook engineering. Quote from MMM (The Mythical Man-Month, book recommended for the course): Brooks's Law ``Adding manpower to a late software project makes it later''

Organization principles to reduce the number of inter-person communication links: hierarchy, layering

To email or to meet:If you need to communicate a message of W words to N people, should you write it up as an email or call a meeting? Assume people's time is equally valuable and your goal is to deliver the message with the least total cost (measured by total time spent by all people including yourself).

Inner works of human mind


Why memory is important

Short-term memory


Long-term memory

Expertise is really about long-term memory

Serial position effect: Recency bias vs. Primacy vias