Content uploaded by Berit Brogaard
Author content
All content in this area was uploaded by Berit Brogaard on May 27, 2018
Content may be subject to copyright.
A preview of the PDF is not available
Deaf hearing: Implicit discrimination of auditory content in a patient with mixed hearing loss
Abstract and Figures
We describe a patient LS, profoundly deaf in both ears from birth, with underdeveloped superior temporal gyri. Without hearing aids, LS displays no ability to detect sounds below a fixed threshold of 60 dBs, which classifies him as clinically deaf. Under these no-hearing-aid conditions, when presented with a forced-choice paradigm in which he is asked to consciously respond, he is unable to make above-chance judgments about the presence or location of sounds. However, he is able to make above-chance judgments about the content of sounds presented to him under forced-choice conditions. We demonstrated that LS has faint sensations from auditory stimuli, but questionable awareness of auditory content. LS thus has a form of type-2 deaf hearing with respect to auditory content. As in the case of a subject with acquired deafness and deaf hearing reported on a previous occasion, LS’s condition of deaf hearing is akin in some respects to type-2 blindsight. As for the case of type 2 blindsight the case indicates that a form of conscious hearing can arise in the absence of a fully developed auditory cortex.
Figures - uploaded by Berit Brogaard
Author content
All figure content in this area was uploaded by Berit Brogaard
Content may be subject to copyright.
... An analogue of blindsight, both type-1 and type-2, can arise in audition as well (Brogaard et al., 2017). It also can be artificially induced by applying transcranial magnetic stimulation (TMS) to the primary visual cortex (Koenig and Ro, 2019). ...
Do perceptual experiences always inherit the content of their neural correlates? Most scientists and philosophers working on perception say 'yes'. They hold the view that an experience's content just is (i.e.is identical to) the content of its neural correlate. This paper presses back against this view, while trying to retain as much of its spirit as possible. The paper argues that type-2 blindsight experiences are plausible cases of experiences which lack the content of their neural correlates. They are not experiences of the stimuli or stimulus properties prompting them, but their neural correlates represent these stimulus properties. The argument doesn't depend on any special view of what it is for an experience to be of a stimulus or stimulus property. The upshot is that, even assuming there is a deep relationship between experiential content and neural content, that relationship is more complex than simple identity.
... We should expect to find all the same dissociations between unlimited and limited forms of learning that we find in healthy subjects with masking and related protocols. Although blindsight is specifically a visual phenomenon, there is some evidence (albeit less compelling evidence) of related phenomena in other sense modalities (for hearing see Brogaard et al. 2017; for olfaction see Zucco et al. 2015). ...
Over the past two decades, Ginsburg and Jablonka have developed a novel approach to studying the evolutionary origins of consciousness: the Unlimited Associative Learning (UAL) framework. The central idea is that there is a distinctive type of learning that can serve as a transition marker for the evolutionary transition from non-conscious to conscious life. The goal of this paper is to stimulate discussion of the framework by providing a primer on its key claims (Part I) and a clear statement of its main empirical predictions (Part II).
... Action influenced by biasing intentions, I will argue, is a kind of skilled, irreflective behavior that is nonetheless agential. 1 There are auditory, tactile and emotional dual streams that parallel the dual visual streams (Romanski et al. 1999;Reed et al. 2005;Brogaard et al. 2017). However, most research has focused on vision. ...
For almost half a century dual-stream advocates have vigorously defended the view that there are two functionally specialized cortical streams of visual processing originating in the primary visual cortex: a ventral, perception-related ‘conscious’ stream and a dorsal, action-related ‘unconscious’ stream. They furthermore maintain that the perceptual and memory systems in the ventral stream are relatively shielded from the action system in the dorsal stream. In recent years, this view has come under scrutiny. Evidence points to two overlapping action pathways: a dorso-dorsal pathway that calculates features of the object to be acted on, and a ventro-dorsal pathway that transmits stored information about skilled object use from the ventral stream to the dorso-dorsal pathway. This evidence suggests that stored information may exert significantly more influence on visually guided action than hitherto assumed. I argue that this, in turn, supports the notion of skilled automatic action that is nonetheless agential. My focus here will be on actions influenced by implicit biases (stereotypes/prejudices). Action that is biased in this way, I argue, is in an important sense intentional and agential.
... For people with inborn disabilities or who have lost certain senses such as sight (blindness) or hearing (deafness), the initiating function is left disabled and their bodies are unable to trigger signals through these receptors. Researchers [25,41] have investigated ways of triggering signals that are alternative to lost senses by attempting to mimic what could have been sensed otherwise. In this way, the human body can develop equivalent electrochemical signals, which the brain can perceive as it would do for the lost senses. ...
At a construction site, workers mainly rely on two senses, which are sight and sound, in order to perceive their physical surroundings. However, they are often hindered by the nature of most construction sites, which are usually dynamic, loud, and complicated. To overcome these challenges, this research explored a method using an embedded sensory system that might offer construction workers an artificial sensing ability to better perceive their surroundings. This study identified three parameters (i.e., intensity, signal length, and delay between consecutive pulses) needed for tactile-based signals for the construction workers to communicate quickly. We developed a prototype system based on these parameters, conducted experimental studies to quantify and validate the sensitivity of the parameters for quick communication, and analyzed test data to reveal what was added by this method in order to perceive information from the tactile signals. The findings disclosed that the parameters of tactile-based signals and their distinguishable ranges could be perceived in a short amount of time (i.e., a fraction of a second). Further experimentation demonstrated the capability of the identified unit signals combined with a signal mapping technique to effectively deliver simple information to individuals and offer an additional sense of awareness to the surroundings. The findings of this study could serve as a basis for future research in exploring advanced tactile-based messages to overcome challenges in environments for which communication is a struggle.
Newell & Shanks (N&S) argue that an explanation for blindsight need not appeal to unconscious brain processes, citing research indicating that the condition merely reflects degraded visual experience. We reply that other evidence suggests blindsighters' predictive behavior under forced choice reflects cognitive access to low-level visual information that does not correlate with visual consciousness. Therefore, while we grant that visual consciousness may be required for full visual experience, we argue that it may not be needed for decision making and judgment.
There are several neuropsychological syndromes in which good residual function is retained in the absence of acknowledged awareness, among them blindsight, amnesia, and unilateral neglect. All of them point to the need in studying conscious awareness not only for an ``on-line'' demonstration of the relevant capacity, but for an independent commentary or classi® catory response by the subject, whether human or animal. The parametric limits of blindsight (visual discrimination without awareness) can be measured using a ``commentary key'' psychophysical paradigm, and the results may possibly allow an approach to identifying neural structures involved in visual awareness. Dans plusieurs syndromes neuropsychologiques, notamment la vision aveugle, l' amne sie et la ne gligence unilate rale, on observe un bon fonctionnement re siduel alors que le patient semble ne pas prendre conscience de perceptions ou des souvenirs. Tous ces syndromes indiquent que dans l' e tude de la prise de conscience, il faut non seulement de montrer ``on line'' que le patient est conscient ou non des e ve nements mais il faut aussi obtenir des indices inde pendant sur l' e tat de conscience du sujet humain ou animal, par un commentaire ou par une re ponse de classi® cation. Les limites parame triques de la vision aveugle (discrimination visuelle dans prise de conscience) peuvent eà tre mesure es en utilisant le paradigme psychophysique du ``commentaire-cle '' et les re sultats obtenus peuvent rendre possible une approche visant aÁ identi® er les structures nerveuses jouant un roà le dans la prise de conscience visuelle. In recent years a surprising fact has emerged from neuropsychological studies of brain- damaged patients with cognitive disorders: in all of the syndromes, robust residual capacities remain of which the subjects themselves are un- aware: they are opaque to the patient but not to the experimenter (cf. reviews by Milner & Rugg,
By characterizing the function of the ventral and dorsal visual streams as, respectively, vision-for-perception and vision-for-action, Milner and Goodale (1995) have brought some action onto the perceptual scene. However, with the distinction of the ventral "what" system and the dorsal "how" system, comes a dilemma: How is the operation of the two systems united toward common goals? This is an example of a binding problem. We propose that for binding these two systems, no mechanism needs to exist in the brain to bring ventral and dorsal representations together. Coherent behavior

may be accomplished by focusing the two streams upon the same external object through a strategy of spatial selection, using either the fovea or selective attention. This strategy exploits the simple fact that two objects cannot occupy the same place at the same time. Other kinds of binding, like that involving the perceptual binding of the elements of a scene into coherent perceptual units, may be accomplished by exploiting other regularities of the environment, such as the likelihood that two simultaneous sounds were caused by a common event. From an evolutionary perspective, the most effective way to cope with the distant environment is to use different but complementary sensors, both contributing to aspects of identification and action guidance. For example, audition plays a role both in perceptual analysis and in action guidance, suggesting the possibility of segregated processing of auditory information. Thus, the functional distinction between a "what" system and a "how" system may not be limited to the visual modality, but may be a fundamental distinction for behavioral control in general.
In man and monkey, absolute cortical blindness is caused by destruction of the optic radiations and/or the primary visual cortex. It is characterized by an absence of any conscious vision, but stimuli presented inside its borders may nevertheless be processed. This unconscious vision includes neuroendocrine, reflexive, indirect and forced-choice responses which are mediated by the visual subsystems that escape the direct cerebral damage and the Ensuring degeneration. While extrastriate cortical areas participate in the mediation of the forced-choice responses, a concomitant striate cortical activation does not seem to be necessary for blindsight. Whether the loss of phenomenal vision is a necessary consequence of striate cortical destruction and whether this structure is indispensable for conscious sight are much debated questions which need to be tackled experimentally.
The phenomenon ‘blindsight’ has received much interest from neuroscientists, philosophers, and psychologists during the last decades. Several researchers seem to agree that blindsight might be of great importance in the ambition to find neural correlates of consciousness. However, the history of blindsight is a history of changing experimental paradigms and very few patients. In late 19th century, researchers debated why lesions to primary visual cortex seemingly left some visual abilities intact in animals, while human patients reported to be blind. From the 1970s until today, experiments have attempted to compare measures of conscious and unconscious perception, suggesting a distinction between visual functions and visual experience. However, more recently, newer methods and an interest in introspective reports have cast doubts about the ‘blindness’ of blindsight. A cautious conclusion is suggested, though current research can be interpreted in different ways. WIREs Cogn Sci 2012 doi: 10.1002/wcs.1194
For further resources related to this article, please visit the WIREs website.