Idioms such as break a leg and piece of cake make up a significant portion of spoken and written discourse. Like other linguistic expressions stemming from conceptual metaphor (e.g., metaphors, similes), idioms serve to provide understanding of one concept in relation to a different concept (e.g., love is a journey). The ability to comprehend figurative expressions has an extended developmental period that begins as young as 5 years and continues into adulthood. The Language Experience Hypothesis attributes figurative language competence to meaningful exposure to figurative expressions. The Global Elaboration Hypothesis, however, proposes that figurative language comprehension depends upon skills needed for general text comprehension (e.g., ability to make inferences, semantic knowledge). Studies with children and adolescents have shown that reading comprehension relates to both idiom familiarity and comprehension. Similar studies have not been conducted with adult struggling readers. This study examined idiom familiarity and comprehension of adult struggling readers (N = 60; M age = 41 years) in relation to their reading skills. The Idiom Familiarity and Idiom Comprehension tasks developed by Nippold and colleagues (1993, 2001) were used, which allowed for comparisons between the performance of adult struggling readers in this study and past research. Participants’ idiom comprehension scores were lower than those of adults studied in previous research, and comparable to those of children reading at similar levels. Their familiarity rankings of individual idioms aligned with the levels established by Nippold and Rudzinski (1993); however, they were less familiar with idioms than the twelfth grade group. Results from a familiarity (high, moderate, low) x context (isolation, story) ANOVA showed story context helped adult struggling readers comprehend more high-familiarity idioms, but hindered comprehension of low-familiarity idioms. Hierarchical regressions revealed that reading comprehension accounted for unique variance over and beyond idiom familiarity and word reading skills for idioms presented in both isolation and story contexts. Findings from this study contribute to the study of figurative language comprehension by examining adults with limited literacy skills. Similarly, these findings contribute to the field of adult literacy by providing initial evidence of adult struggling readers’ familiarity and comprehension of idioms.

Some researchers that work with metaphor theory claim that metaphors and figurative language are understood and processed just as easily as literal language. However, as this thesis will explore in detail, other research indicates that such is not always the case. That is, if the category of metaphor is further subcategorized into conventional and non-conventional metaphor, the scope will change because of the fact that it is possible to argue that non-conventionalized metaphors require a more conscious path of processing. In order to explain this alternative path, there are two primary approaches to language processing worth introducing: implicit and explicit. These approaches vary in required attention and speed of processing. With regards to conscious effort, these approaches are rather similar to the way in which we process conventionalized and non-conventionalized metaphors. Conventional metaphors are processed more quickly and easily than non-conventional ones. Hence, the claim that all metaphors are similarly processed may not always be true. Furthermore, an individual’s level of proficiency presumably correlates with speed in language processing. However, if non-conventional metaphor requires a more deliberate path of processing, this thesis assumes that the processing of this type of metaphor will be relatively unaffected by proficiency level, thus causing informants to process them in similar manners. In this thesis, 24 non-native speakers (NNS), categorized into intermediate proficient and advanced proficient, and seven native speakers (NS) were tested with an RT-test on subjective metaphor comprehension. Results were compared using mean response times and standard deviations, as well as looking at correlations and coefficient of variation. The results showed a distinct difference in processing speed with conventional metaphors being processed significantly faster. Moreover, the findings indicate that conventional metaphor processing speed seems to be predicted by proficiency, whilst non-conventional processing speed is not. The RT differences remained relatively consistent in both conventional and non-conventional metaphor processing, but when taking correlations, variance and coefficient of variation into consideration, the findings indicate that these other factors help level out the differences in non-conventional metaphor processing in more subtle ways than simply by RT’s.

The thesis deals with the theory of metaphor in selected pieces of research that focus on autism spectrum disorders. Patients with autism spectrum disorders show weakened ability to communicate and they have trouble understanding everyday social interactions as they are not able to identify with thoughts and feelings of others. They also have trouble understanding metaphors, irony, hyperbolical speech, etc. In their book Metaphors we live by Lakoff and Johnson claim that our language and our thinking are based on metaphors, i.e. on abstraction. The hypothesis is that various pieces of research focusing on how people on the autism spectrum understand metaphors draw on different definitions of metaphor and different approaches to it. The theory of metaphor that is presented in Lakoff's and Johnson's work should be able to provide theoretical framework for coherent understanding of a metaphor. It should also have the potential to point out the differences between particular pieces of research and possible shortages within them.