Key Study: Levels of Processing (Craik and Tulving, 1975)

Travis DixonCognitive Psychology

Background Information

The multi-store model of memory (MSM), while straightforward, seemingly common sense, and with plenty of empirical support, is not without its limitations. Do you really need to pay attention to, and rehearse, all sensory information in order for it to be transferred to your long-term memory? Take, for instance, experiences of traumatic or emotionally shocking events (e.g. Flashbulb memories). Why do these memories seem to skip the STS and end up straight in our LTS? Do you find it easier to remember what you learn in school if you can apply it your own life?

What the MSM fails to address is that we don’t process all sensory information in the same way. Some requires very little cognitive effort to process (e.g. recognising a colour), while others take much more cognitive effort (e.g. figuring out the meaning of a word you don’t know based on the context in which it’s used).

Craik and Lockhart’s Levels of Processing (LOP) model aimed to address the processing of information that was missing from the MSM.

Description of the Model[1]

In 1972, Craik and Lockhart proposed a new model of memory formation related to depth of processing. They theorized that not all sensory information is processed the same and thus is transferred to our LTS at different rates. That is to say, information that requires more cognitive processing (“deeper processing”) will be more likely remembered than information requiring shallow processing.

Thus, the fundamental claim of the LOP model is that the deeper information is processed, the more likely it is to be remembered.

According to LOP model, there are three levels at which information can be processed. In order from shallowest to deepest, they are:

  • Structural Level; the physical characteristics of sensory information (e.g. shape, colour, size);
  • Phonological Level: the sounds of information;
  • Semantic Level: the meaning of the information processed;

Thus, the fundamental claim of the LOP model is that the deeper information is processed, the more likely it is to be remembered.

Supporting Studies

Craik and Tulving conducted an experiment to determine whether the level of processing has an influence on recall. They used the incidental learning paradigm in their studies, which is when participants are not told explicitly that they will be tested.

The researchers carried out numerous experiments[2] to demonstrate their findings. One of these experiments involved 24 paid male and female participants who were presented with 60 questions and a five letter, one syllable, concrete noun as a possible response (e.g. shark; cloud; crate). The questions were written in a way so that participants either had to select “yes” or “no” as the correct answer (they had their hands on either button to signify their answer). The participants were told the experimenters were researching perception and speed of reaction. The types of questions required participants to process the information at different levels.

For instance:

  • Structural: “Is the word in capital letters.?”
  • Phonological: “Does the word rhyme with WEIGHT?”’
  • Semantic: “Would the word fit in the sentence: “He met a ……. in the street?”

The researchers measured the time it took participants to provide an answer (latency) and how many words participants could correctly recall from a list of 180 (the 60 original + 120 “distractors”). Participants were asked to circle those words they identified. The results supported their hypothesis: words that were processed semantically had the highest rate of accurate recall %, second was phonological and finally there was structural.[3]

The researchers replicated their experimental design numerous times, with slight modifications to test different hypotheses. The results of these experiments supported the original hypothesis: the deeper the information is processed, the more likely it is to be remembered.

Critical Thinking Questions

  • What are the strengths and limitations of the LOP model of memory? (Evaluation)
  • How do the results of LOP experiments using the incidental learning paradigm challenge aspects of the MSM? (Analysis; Application; Synthesis; Evaluation)
  • How could you apply principles from the LOP (and MSM) to your own life? (Application)


Craik, Fergus I. M., and Endel Tulving. “Depth of Processing and the Retention of Words in Episodic Memory.” Journal of Experimental Psychology: General 104.3 (1975): 268-94. Web. Accessed from here.

Gross, Richard D. Key Studies in Psychology. London: Hodder & Stoughton, 2003. Print.

[1] Craik and Lockhart claim that LOP is not a theory of memory – it’s a framework for investigating memory. (Gross, p56). Thus, we’ll refer to it as a model, as opposed to a theory.

[2] If you are doing your IA based on LOP, you need to read this original full report.

[3] Their full report consists of ten different experiments, so you don’t need to know precise results.