Should absolute pitch be considered as a unique kind of absolute sensory judgment in humans? A systematic and theoretical review of the literature

Absolute pitch is the name given to the rare ability to identify a musical note in an automatic and effortless manner without the need for a reference tone. Those individuals with absolute pitch can, for example, name the note they hear, identify all of the tones of a given chord, and/or name the pitches of everyday sounds, such as car horns or sirens. Hence, absolute pitch can be seen as providing a rare example of absolute sensory judgment in audition. Surprisingly, however, the intriguing question of whether such an ability presents unique features in the domain of sensory perception, or whether instead similar perceptual skills also exist in other sensory domains, has not been explicitly addressed previously. In this paper, this question is addressed by systematically reviewing research on absolute pitch using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) method. Thereafter, we compare absolute pitch with two rare types of sensory experience, namely synaesthesia and eidetic memory, to understand if and how these phenomena exhibit similar features to absolute pitch. Furthermore, a common absolute perceptual ability that has been often compared to absolute pitch, namely colour perception, is also discussed. Arguments are provided supporting the notion that none of the examined abilities can be considered like absolute pitch. Therefore, we conclude by suggesting that absolute pitch does indeed appear to constitute a unique kind of absolute sensory judgment in humans, and we discuss some open issues and novel directions for future research in absolute pitch.

Autism Spectrum Disorder and Savant Syndrome: A Systematic Literature Review

Objectives

This study aimed to analyze research trends in autism spectrum disorder (ASD) and savant syndrome and their cognitive characteristics through a systematic literature review. The objectives of this study were to establish an overview of research trends in ASD and savant syndrome, analyze the overall characteristics of individuals with ASD and savant syndrome, and examine their cognitive characteristics.

Methods

For the systematic literature review, three criteria were used to select review articles: 1) literature from peer-reviewed journals, published in the past 15 years, from 2008 to 2022; 2) subjects with ASD and savant syndrome; 3) study objectives focused on the basic phenomenon and cognitive characteristics of ASD and savant syndrome. Finally, based on the selection criteria, a total of 40 articles were included.

Results

Five themes and nine subthemes were derived from the analysis of 40 studies. The five main themes were as follows: 1) What is savant syndrome? 2) Demographic characteristics of savant syndrome; 3) Spectra of savant syndrome; 4) Savant syndrome and ASD; and 5) Cognitive characteristics of ASD with savant syndrome. The subthemes of the cognitive characteristics were weak central coherence, detail-focused cognitive processing, enhanced perceptual functioning, and hyper-systemizing.

Conclusion

Several studies have been conducted to understand ASD and savant syndrome; however, no single theory can specify the cognitive characteristics of people with ASD and savant syndrome. Therefore, further systematic and multi-layered research on ASD and savant syndrome are required for more comprehensive results.

The Savant Syndrome: a Gift or a Disability? A Deeper Look into Metabolic Correlates of Hidden Cognitive Capacity

Savant syndrome is a rare and unusual condition that occurs in the presence of severe developmental disabilities, disorders, and injuries. The syndrome can be congenital from birth to childhood or acquired as a result of a brain injury or damage to the central nervous system. There are several findings that indicate that savant syndrome usually occurs with significant brain metabolism alterations resulting in critical brain network changes. These types of changes in the brain are usually explained by the "tyranny of the left hemisphere" theory, which indicates the inhibition of the left hemisphere to allow the right hemisphere to develop savant abilities. Another way to temporarily simulate these types of changes in the brain can be through different neuromodulation techniques such as transcranial magnetic stimulation and transcranial direct current stimulation. Such neuromodulation techniques might help us discover the "hidden talent" potential through modulating the brain network metabolism. We herein discussed the types of savant syndrome along with its relation to specific neurometabolic network alterations. Furthermore, we provide a perspective on how newly developed neuromodulation and cognitive rehabilitation techniques can help simulate savant syndrome in healthy individuals through modulating the brain network activity.

Synaesthetes show advantages in savant skill acquisition: Training calendar calculation in sequence-space synaesthesia

Previous research has suggested that synaesthetic experiences may create the foundation for superior skills to emerge of the type found in savant syndrome (e.g., Simner, Mayo, & Spiller, 2009). People with sequence-space synaesthesia experience units of time (e.g., days, months, years) as a pattern in space, either within the mind's eye or as a 3d projection outside of the body. Our study investigates whether sequence-space synaesthesia facilitates the learning of the savant skill known as 'calendar calculation' where an individual can give the correct day of the week for any given date (e.g., 18th September 1990 was a Tuesday). Using a novel experimental methodology, we trained a group of sequence-space synaesthetes as well as non-synaesthete controls how to calendar calculate over two weeks with a final calendar calculation test in the third week. We show for the first time that calendar calculation is relatively easy to acquire: following training sessions totalling 1 h participants could select a day, from a set of several thousand, within ∼10 sec and with ∼80% accuracy. Synaesthetes were not found to have improved abilities from the start, but they outperformed controls in our final calendar calculation test. We suggest that sequence-space synaesthesia may have provided an advantage in performing calendar calculation after the opportunity for initial learning had taken place. This supports the notion of synaesthesia as a foundation for superior, and perhaps sometimes savant-like, skills.

Savant syndrome has a distinct psychological profile in autism

Background

Savant syndrome is a condition where prodigious talent can co-occur with developmental conditions such as autism spectrum conditions (autism). It is not yet clear why some autistic people develop savant skills while others do not.

Methods

We tested three groups of adults: autistic individuals who have savant skills, autistic individuals without savant skills, and typical controls without autism or savant syndrome. In experiment 1, we investigated the cognitive and behavioural profiles of these three groups by asking participants to complete a battery of self-report measures of sensory sensitivity, obsessional behaviours, cognitive styles, and broader autism-related traits including social communication and systemising. In experiment 2, we investigated how our three groups learned a novel savant skill-calendar calculation.

Results

Heightened sensory sensitivity, obsessional behaviours, technical/spatial abilities, and systemising were all key aspects in defining the savant profile distinct from autism alone, along with a different approach to task learning.

Conclusions

These results reveal a unique cognitive and behavioural profile in autistic adults with savant syndrome that is distinct from autistic adults without a savant skill.

Neural mechanisms of savant calendar calculating in autism: an MEG-study of few single cases

This study contrasted the neurological correlates of calendar calculating (CC) between those individuals with autism spectrum disorder (ASD) and typically developing individuals. CC is the ability to correctly and quickly state the day of the week of a given date. Using magnetoencephalography (MEG), we presented 126 calendar tasks with dates of the present, past, and future. Event-related magnetic fields (ERF) of 3000ms duration and brain activation patterns were compared in three savant calendar calculators with ASD (ASDCC) and three typically developing calendar calculators (TYPCC). ASDCC outperformed TYPCC in correct responses, but not in answering speed. Comparing amplitudes of their ERFs, there was a main effect of group between 1000 and 3000ms, but no further effects of hemisphere or sensor location. We conducted CLARA source analysis across the entire CC period in each individual. Both ASDCC and TYPCC exhibited activation maxima in prefrontal areas including the insulae and the left superior temporal gyrus. This is in accordance with verbal fact retrieval and working memory as well as monitoring and coordination processes. In ASDCC, additional activation sites at the right superior occipital gyrus, the right precuneus, and the right putamen point to visual-spatial strategies and are in line with the preference of autistic individuals for engaging posterior regions relatively more strongly in various reasoning and problem solving tasks.