What type of intelligence involves information processing abilities such as short-term memory, ability to discern relations between visual stimuli, and speed of synthesizing new information?

The correct answer is fluid intelligence.

There are two factors of general intelligence in psychology, and those are fluid and crystallized. Both were created by Raymond Cattel, a famous psychologist, and later on further developed by his student. Fluid intelligence requires you to acquire new skills in order to solve problems, whereas crystallized intelligence means that you will already have an acquired set of skills necessary for solving a problem.