Kulpe, arguing against Wundt, made the obvious point that some thoughts were "imageless" - such as "doubt". In fact, the very search for a thought was imageless.

Kulpe used systematic experimental introspection to investigate these higher forms of thought. (Today, we call this "thinking real hard".) He used this awesome discovery in research: he gave subjects problems then asked them to report on the mental operations they engaged in - they were asked to give the type of thinking used at each stage.- Wundt's elements of sensation were not enough to explain the act of judging, again proving the awesome superiority of Kulpe over Wundt.

Kuple introduced the concept of the Mental set. Kulpe found that focusing subjects on a particular problem created a determining tendency that persisted until the problem was solved- even when participants were unaware of this process. Today, this problem is known as "desk topping" or the phenomena of how concentrating on a problem creates a "paradigm" in our minds. It is interesting to note that this mindset is behind the phenomena of why the advice to "forget about the problem for awhile, and the solution will come" works. It is because Kulpe is right, yet again. Focusing on a problem creates a limited paradigm, and by "forgetting about the problem" we lose the paradigm. Now that the filter, which is limiting our thoughts, is gone, our minds are free to consider thoughts that were outside the paradigm. Typically, the answer comes within moments.

Where do Mental Sets come from?

Mental sets result from past experience - these experiences create sets of expectations concerning how a problem is to be solved.

Experimental support for Mental Sets

Kulpe showed that the mental set could be illustrated experimentally, through the use of cards that were made up of nonsense syllables with different color backgrounds. The simple environmental stimuli of these cards did not automatically create sensations that became images...rather, the process of attention determined which stimuli (color or syllable) was retained. This result supported Wundt's associationism, and went against the works of Titchner, whose influence was already fading fast.

Kulpe also noted that some problems have motivational properties, which makes his theory a forerunner of gestalt theory. He felt that motivations cause subjects to continue to apply mental operations until a solution is achieved. For more on this line of thought, please see the gestalt page.