Imagery agnosia and its phenomenology

Lack of vivid sensory imagery has recently become an active subject of research, under the name of aphantasia. Extremely vivid imagery, or hyperphantasia, is at the other end of the spectrum of individual differences. While most research has focused on visual imagery in this paper I argue that from a neuropsychological perspective this phenomenon is much more widespread, and should be categorized as imagery sensory agnosia. After over twenty years of learning to play music phenomenology of auditory imagery agnosia is described from the first-person perspective. Reflections on other forms of imagery agnosia and deficits of autobiographical memories are presented and a hypothesis about putative brain processes that can account for such phenomena is discussed. Extreme individual differences in imagery and in autobiographical memory have implications for many fields of study, from consciousness research to education.

The eyes have it: The pupillary light response as a physiological index of aphantasia, sensory and phenomenological imagery strength

The pupillary light response is an important automatic physiological response that optimises light reaching the retina. Recent work has shown that the pupil also adjusts in response to illusory brightness and a range of cognitive functions, however, it remains unclear what exactly drives these endogenous changes. Here we show that the imagery pupillary light response correlates with objective measures of sensory imagery strength. Further, the trial-by-trial phenomenological vividness of visual imagery is tracked by the imagery pupillary light response. We also demonstrated that there was no evidence for an imagery pupillary light response in a group of individuals without visual imagery (aphantasia), however, they did show perceptual pupil light responses and pupil dilation with larger cognitive load. Our results provide evidence that the pupillary light response indexes the sensory strength of visual imagery and also provides the first physiological validation of aphantasia.

What is the Link Between Mental Imagery and Sensory Sensitivity? Insights from Aphantasia

People with aphantasia have impoverished visual imagery so struggle to form mental pictures in the mind's eye. By testing people with and without aphantasia, we investigate the relationship between sensory imagery and sensory sensitivity (i.e., hyper- or hypo-reactivity to incoming signals through the sense organs). In Experiment 1 we first show that people with aphantasia report impaired imagery across multiple domains (e.g., olfactory, gustatory etc.) rather than simply vision. Importantly, we also show that imagery is related to sensory sensitivity: aphantasics reported not only lower imagery, but also lower sensory sensitivity. In Experiment 2, we showed a similar relationship between imagery and sensitivity in the general population. Finally, in Experiment 3 we found behavioural corroboration in a Pattern Glare Task, in which aphantasics experienced less visual discomfort and fewer visual distortions typically associated with sensory sensitivity. Our results suggest for the very first time that sensory imagery and sensory sensitivity are related, and that aphantasics are characterised by both lower imagery, and lower sensitivity. Our results also suggest that aphantasia (absence of visual imagery) may be more accurately defined as a subtype of a broader imagery deficit we name dysikonesia, in which weak or absent imagery occurs across multiple senses.

‘IT SOUNDED SO UNLIKE INDIA’: AUDITORY PERCEPTION IN ‘THE SECRET GARDEN’ BY F. H. BURNETT

Children’s literature has traditionally employed images of different sensory modalities to make the experience of the main characters more accessible to young readers. We believe that auditory imagery is an integral part of the sensory imagery repertoire of any text written for children, and auditory perception in a literary text reflects the way of interaction between the characters and the world around them at various stages of their spiritual journey. Being a traditional coming-of-age novel, The Secret Garden by F. H. Burnett shows a specific connection between auditory imagery and the plot of the novel since it reveals the changes in the main heroine’s character and highlights her growing need to accept another point of view. Eventually, Mary Lennox, the main character of the novel, becomes ready to hear other people: her initial indifference towards the surrounding is gradually being replaced by her sincere wish to listen to the Yorkshire dialect, speak her native tongue, and believe in the curing effect of the word. With the change of the spatial imagery of the text (from British India in the first chapters to the restricted space of the garden in the Yorkshire estate Misselthwaite Manor in the second part of the book), the heroine’s inner growth becomes more obvious, and the foregrounding of the sensory imagery (including auditory) grows more vivid. The spiritual transformation experienced by Mary Lennox affects other characters of the story and even leads to overshadowing of her role at the end of the novel. From the perspective of auditory imagery, Burnett creates a circular structure, making her heroine go from a lack of audio perception – through unhackneyed auditory sketches and quotations from classic novels – to a total silencing of the main heroine at the end of the novel.

Cortical excitability controls the strength of mental imagery

Mental imagery provides an essential simulation tool for remembering the past and planning the future, with its strength affecting both cognition and mental health. Research suggests that neural activity spanning prefrontal, parietal, temporal, and visual areas supports the generation of mental images. Exactly how this network controls the strength of visual imagery remains unknown. Here, brain imaging and transcranial magnetic phosphene data show that lower resting activity and excitability levels in early visual cortex (V1-V3) predict stronger sensory imagery. Further, electrically decreasing visual cortex excitability using tDCS increases imagery strength, demonstrating a causative role of visual cortex excitability in controlling visual imagery. Together, these data suggest a neurophysiological mechanism of cortical excitability involved in controlling the strength of mental images.

Iconicity in Word Learning and Beyond: A Critical Review

Interest in iconicity (the resemblance-based mapping between aspects of form and meaning ) is in the midst of a resurgence, and a prominent focus in the field has been the possible role of iconicity in language learning. Here we critically review theory and empirical findings in this domain. We distinguish local learning enhancement (where the iconicity of certain lexical items influences the learning of those items) and general learning enhancement (where the iconicity of certain lexical items influences the later learning of non-iconic items or systems). We find that evidence for local learning enhancement is quite strong, though not as clear cut as it is often described and based on a limited sample of languages. Despite common claims about broader facilitatory effects of iconicity on learning, we find that current evidence for general learning enhancement is lacking. We suggest a number of productive avenues for future research and specify what types of evidence would be required to show a role for iconicity in general learning enhancement. We also review evidence for functions of iconicity beyond word learning: iconicity enhances comprehension by providing complementary representations, supports communication about sensory imagery, and expresses affective meanings. Even if learning benefits may be modest or cross-linguistically varied, on balance, iconicity emerges as a vital aspect of language.