From Perception to Metacognition: Auditory and Olfactory Functions in Early Blind, Late Blind, and Sighted Individuals

Abstract

Although evidence is mixed, studies have shown that blind individuals perform better than sighted at specific auditory, tactile, and chemosensory tasks. However, few studies have assessed blind and sighted individuals across different sensory modalities in the same study. We tested early blind (n = 15), late blind (n = 15), and sighted (n = 30) participants with analogous olfactory and auditory tests in absolute threshold, discrimination, identification, episodic recognition, and metacognitive ability. Although the multivariate analysis of variance (MANOVA) showed no overall effect of blindness and no interaction with modality, follow-up between-group contrasts indicated a blind-over-sighted advantage in auditory episodic recognition, that was most pronounced in early blind individuals. In contrast to the auditory modality, there was no empirical support for compensatory effects in any of the olfactory tasks. There was no conclusive evidence for group differences in metacognitive ability to predict episodic recognition performance. Taken together, the results showed no evidence of an overall superior performance in blind relative sighted individuals across olfactory and auditory functions, although early blind individuals exceled in episodic auditory recognition memory. This observation may be related to an experience-induced increase in auditory attentional capacity.

No Sensory Compensation for Olfactory Memory: Differences between Blind and Sighted People

“…Further, several studies demonstrated that blind people performed better than sighted individuals in olfactory discrimination, which is often considered to reflect short-term olfactory memory ( Cuevas et al, 2009 , 2010 ; Rombaux et al, 2010 ; Renier et al, 2013 ; Çomoğlu et al, 2015 ). However, in the case of this olfactory ability the results were not consistent – other researchers demonstrated that olfactory discrimination skills do not depend on visual status ( Schwenn et al, 2002 ; Beaulieu-Lefebvre et al, 2011 ; Oniz et al, 2011 ; Luers et al, 2014 ; Majchrzak and Eberhard, 2014 ; Cornell Kärnekull et al, 2016 ; Guducu et al, 2016 ; Sorokowska, 2016 ).…”

“…Overall, data suggest that olfactory memory of blind people could be better than that of the sighted individuals. However, a recent study did not confirm this hypothesis ( Cornell Kärnekull et al, 2016 ). Cornell Kärnekull et al (2016) used a 24-item olfactory episodic recognition test to compare 30 blind individuals aged 26–73 years ( M = 55.5, SD = 12) to a corresponding group of sighted individuals.…”

“…However, a recent study did not confirm this hypothesis ( Cornell Kärnekull et al, 2016 ). Cornell Kärnekull et al (2016) used a 24-item olfactory episodic recognition test to compare 30 blind individuals aged 26–73 years ( M = 55.5, SD = 12) to a corresponding group of sighted individuals. The participants were further asked to identify a subsample of 12 highly familiar odors.…”

“…Further, in a study employing 96 subjects tested with 16-item Test for Olfactory Memory (TOM; Croy et al, 2015 ), olfactory recognition scores of participants older than 60 years were lower than scores obtained by age groups 18–30 and 31–60. However, it is not clear how age affects olfactory memory in blind individuals, as the effect of this variable was not analyzed in the previous study involving this group ( Cornell Kärnekull et al, 2016 ).…”

“…Nevertheless, compensatory effects of visual impairment on olfactory memory might be very complex, as it seems to be the case for olfactory compensation in general ( Kupers and Ptito, 2014 ). Therefore, due to a relatively small sample size, Cornell Kärnekull et al (2016) could not explore all possibilities in their research. For example, age is an important variable that is related both to olfactory acuity ( Sorokowska et al, 2015b ) and memory ( Choudhury et al, 2003 ).…”