
Kinds of human memory
There are three main kinds of human memory. Sensory memory is very fast memory in which the stimuli of our senses are stored for a short period. During this instant, the information goes through a pre-attentive selection phase after which the relevant information is handed over to working memory. Working memory is pretty fast memory that is responsible for the processing and temporary storage of information. It deals with verbal and visual interpretation and contains a subsystem for attention management. Next, long-term memory is slow but virtually unlimited memory that stores information in the form of cognitive schemas, which are composed of patterns of connected elementary facts. Because working memory has a limited capacity and information can only be stored in this memory for a short period, it is important to use it effectively when dealing with highly complex tasks.

Types of cognitive load
When solving problems, information needs to be loaded in working memory to determine, execute and administer the steps for solving the problems. This information forms intrinsic load of working memory. There is also extraneous load, which is the caused by the necessity to translate between mental and external representations of information. For example, the interpretation of letter symbols as words with meaning has a big component of external cognitive load. Finally, germane load is generated by learning efforts. More in particular, it is the load for acquiring and automating cognitive schemas for long-term memory. Furthermore, a distinction can be made between the overall cognitive load (the total amount of information sequentially loaded in working memory for performing a specific task) and instantaneous cognitive load (the amount of information that is loaded in working memory at a certain point in time).

Cognitive Load Theory
Although there appears to be a limit on the amount of units of information that can be loaded simultaneously in working memory, there seems to be no constraint on the size and complexity of these units of information. More specifically, it is believed that one unit of information loaded in working memory (often referred to as 'information chunk') corresponds with one cognitive schema in long-term memory. Nevertheless, even when big chunks of information can be loaded as one unit, the limited capacity of working memory can be insufficient and cognitive overload results. When the working memory is overloaded, people stop learning (reducing germane load), become slower and make more errors. Overload thus needs to be avoided for effective and efficient problem solving.

Cognitive Fit Theory
The Cognitive Fit Theory states that humans are able to solve problems more effectively and efficiently if the representation of the input material of a certain task 'fits' with the task itself. In such case, translating between the external and internal representation of relevant information takes less effort (less extraneous load). For example, when a task involves exploring relationships between data a visual representation such as a diagram is preferred. For more statistical purposes such as determining the average of a series of numbers a textual representation in the form of a list or table is more cognitive efficient. Whereas the main focus of Cognitive Fit Theory is on the match between problem representation and task, a secondary effect is described as the match between the task representation and its performer. For example, most people excel in either graphical or logical tasks.

Extending
the Cognitive Fit Theory
I investigate whether cognitive fit also applies on intrinsic load. Is it productive to match the problem solving strategy to the performer of the task and to the task itself? For example, some problem solvers process information sequentially, whereas other have a global approach. Should they solve problems in a different way (sequentially versus globally) to improve effectiveness and efficiency of problem solving?