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Blindsight is a phenomenon in which patients suffering damage to the primary visual cortex (V1) perceive themselves as blind, but nonetheless seem to have some residual capacity to distinguish between visual stimuli better than chance. Blindsight can be divided into two subtypes: blindsight type I and blindsight type II. Blindsight type I is defined as visual capacity in the absence of acknowledged awareness. Patients with blindsight type II have visual capacity with some feeling or sensation in the blind field. Visual pathways bypassing V1 are assumed to be responsible for the residual capacity in blindsight. To investigate whether these pathways are present in healthy individuals we examined if it is possible to induce blindsight in healthy individuals by reviewing studies that have tried to induce blindsight with transcranial magnetic stimulation (TMS). We found that TMS might be able to induce blindsight type I of side detection. We also found that TMS might be able to induce blindsight type II of colour, orientation, and trustworthiness. Further, we found that both conscious and unconscious perception of shapes are dependent on processing in early visual cortex (EVC) in healthy individuals. We conclude that the full capacity seen in blindsight is most probable caused by neural reorganisation post trauma. The visual pathways bypassing V1 are, if present in healthy individuals, too weak to influence behaviour with the possible exception of side detection. Additionally, we conclude that the use of a binary awareness scale in blindsight studies fails to capture vaguely seen stimuli.

This thesis investigated the processing of emotional stimuli by the visual system, and how the processing of emotions interacts with visual awareness. Emotions have been given ‘special’ status by some previous research, with evidence that the processing of emotions may be relatively independent of striate cortex, and less affected by disruption to awareness than processing of emotionally neutral images. Yet the extent to which emotions are ‘special’ remains questionable. This thesis focused on the processing of emotional stimuli when activity in V1 was disrupted using transcranial magnetic stimulation (TMS), and whether emotional properties of stimuli can be reliably discriminated, or affect subsequent responses, when visibility is low. Two of the experiments reported in this thesis disrupted activity in V1 using TMS, Experiment 1 with single pulses in an online design, and Experiment 2 with theta burst stimulation in an offline design. Experiment 1 found that a single pulse of TMS 70-130 ms following a presentation of a body posture image disrupted processing of neutral but not emotional postures in an area of the visual field that corresponded to the disruption. Experiment 2 did not find any convincing evidence of disruption to processing of neutral or emotional faces. From Experiment 1 it would appear that emotional body posture images were relatively unaffected by TMS, and appeared to be robust to disruption to V1. Experiment 2 did not add to this as there was no evidence of disruption in any condition. Experiments 3 and 4 used visual masking to disrupt awareness of emotional and neutral faces. Both experiments used a varying interval between the face and the mask stimuli to systematically vary the visibility of the faces. Overall, the shortest SOA produced the lowest level of visibility, and this level of visibility was arguably outside awareness. In Experiment 3, participants’ ability to discriminate properties of emotional faces under low visibility conditions was greater than their ability to discriminate the orientation of the face. This was despite the orientation discrimination being much easier at higher levels of visibility. Experiment 4 used a gender discrimination task, with emotion providing a redundant cue to the decision (present half of the time). Despite showing a strong linear masking function for the neutral faces, there was no evidence of any emotion advantage. Overall, Experiment 3 gave some evidence of an emotion advantage under low visibility conditions, but this effect was fairly small and not replicated in Experiment 4. Finally, Experiments 5-8 used low visibility emotional faces to prime responses to subsequent emotional faces (Experiments 5 and 6) or words (Experiments 7 and 8). In Experiments 5, 7 and 8 there was some evidence of emotional priming effects, although these effects varied considerably across the different designs used. There was evidence for meaningful processing of the emotional prime faces, but this processing only led to small and variable effects on subsequent responses. In summary, this thesis found some evidence that the processing of emotional stimuli was relatively robust to disruption in V1 with TMS. Attempts to find evidence for robust processing of emotional stimuli when disrupted with backwards masking was less successful, with at best mixed results from discrimination tasks and priming experiments. Whether emotional stimuli are processed by a separate route(s) in the brain is still very much open to debate, but the findings of this thesis offers small and inconsistent evidence for a brain network for processing emotions that is relatively independent of V1 and visual awareness. The network and nature of brain structures involved in the processing of subliminal and low visibility processing of emotions remains somewhat elusive.

This paper is an examination of the horror elements found in Peter Watts’ Blindsight. In depicting an encounter with aliens, this science fiction novel explores topics such as the nature of sentience, mankind’s relationship with technology, posthumanism, and the limitations of the human body and mind. Blindsight also envisions entities (aliens, vampires, and artificial intelligences) capable of interacting with material realities inaccessible to human beings. Using Levi R. Bryant’s machine-oriented ontology, this thesis demonstrates how Watts employs these themes and issues to problematize anthropocentrism and the notion of selfhood. These elements—and more—will be discussed and shown to match the criteria associated with ontological horror.

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