The octopus has steadily been attracting the attention of philosophy and neuroscience due to its versatile behaviour, decentralized cognitive architecture, and embodied and dynamical motor control operations. This study is a philosophical investigation of the implications which the octopus nervous system raises for theories of cognition and the structure of the mind, grounded in the results of neuroscientific and behavioural studies on octopuses.
The octopus is endowed with a sophisticated behavioural repertoire comparable to that associated with creatures with integrated nervous systems (i.e. vertebrates), yet its cognitive architecture is highly decentralized. The octopus’s neuroanatomy entails that the brain receives little proprioceptive input, and that the bulk of motor control takes place within the arm nervous system with little central involvement. Taken together with the premise of isomorphism between the organization of a creature’s nervous system and the structure of its mind, these facts about the octopus call into question a number of accepted views on the causal interrelations between the brain, mind, and behaviour.
I argue that the octopus raises the need to re-examine a number of established commitments concerning the structure of minds and their role in cognitive architectures. In particular, I present the octopus as a counterexample to the widely held view that a unified mind—one whose functions include integrating information and generating the motor commands involved in goal-directed actions—is necessary to produce intelligent behaviour.

Background: Theory of Mind (ToM) refers to the ability to comprehend and anticipate the thoughts, feelings and intentions of others. Two ToM subsystems are mediated by dissociable yet interacting prefrontal cortex (PFC) networks; cognitive (understanding intentions and beliefs; dorsolateral PFC) and affective (understanding feelings; ventromedial PFC). How aging affects ToM is unclear, with inconsistent results to date. Across studies variable ToM tasks are utilized, with many lacking control conditions, making interpretation and cross-study comparisons difficult. This study utilised a larger battery of ToM tasks, assessing both cognitive and affective ToM.

Methods: 31 younger (YA; 18-30 years) and 39 older adults (OA; 60+ years) completed 8 ToM tasks (4 affective and 4 cognitive). Performances of YA and OA groups on individual tasks were compared. Principal components analysis was then performed to confirm the classification of ToM tasks as affective or cognitive; composite scores of each ToM subtype were then calculated. Separate linear regression models were conducted to examine whether age was a significant predictor of affective, and cognitive, ToM composite scores in the OA.

Results: YA outperformed OA on three ToM tasks. Age was a significant predictor for cognitive, but not affective, ToM performance.

Conclusion: There are subtle differences between YA and OA on some individual ToM tasks, but not others. Age-related decline appears limited to cognitive ToM. Age-related change in dorsolateral PFC might underlie changes in cognitive ToM, and these changes may precede changes in ventromedial PFC and any behaviourally detectable changes in affective ToM.

The capacity to infer the thoughts, beliefs, and perspectives of others is fundamental to successful social interactions, and relies upon theory of mind processing (ToM). While the integrity of the prefrontal cortices is crucial for ToM performance, much less is known regarding the contribution of anterior temporal regions. Here we investigated ToM in the behavioural variant of frontotemporal dementia (n = 10) and semantic dementia (n = 11); neurodegenerative disorders characterised by differential patterns of prefrontal and anterior temporal lobe atrophy, respectively. A simple cartoons task was used consisting of Physical (no ToM attribution required) and Mental (ToM attribution required) components. Relative to Controls (n = 14), significant deficits were evident for Physical and Mental cartoons in both patient groups. When we controlled for semantic comprehension, however, deficits on the Physical cartoons were ameliorated in semantic dementia. Critically, profound ToM deficits persisted on the Mental cartoons in both patient groups. Voxel-based morphometry analyses revealed significant associations between ToM capacity and grey matter intensity in bilateral anterior temporal and orbitofrontal cortices. Notably, the right anterior temporal pole emerged as the common neural substrate of ToM deficits across the patient groups. Our study confirms recent reports of marked deficits in ToM reasoning in semantic dementia which are not exclusively attributable to semantic processing impairments and demonstrates the pivotal role of right anterior temporal lobe structures in supporting complex social cognitive functions.

Recent studies show physiological responses to images suppressed from awareness, indicating unconscious perception. Such findings demonstrate similarities between conscious and unconscious perception, but the subjective difference between these modes raises the question of how they differ at the physiological level. Consciously viewed emotional images evoke a coherent array of physiological responses across multiple systems, but to date, physiological responses produced without stimulus awareness have largely been assessed using single measures. Would emotional images presented outside awareness also evoke a coherent set of physiological responses? Here, we measured four responses simultaneously – electrodermal response, phasic heart rate, startle eyeblink reflex, and post-auricular reflex. Participants viewed arousing emotional images (both positive and negative), which were occasionally accompanied by sudden bursts of white noise to elicit startle reflexes. For half of the participants, the images were masked from awareness using continuous flash suppression. The aware group showed the typical coherent pattern of physiological responses to emotional (compared to neutral) images: larger electrodermal responses, increased heart rate deceleration, potentiated eyeblink reflexes during negative images and potentiated post-auricular reflexes during positive images. In contrast, we found a striking dissociation between measures for the unaware group: electrodermal responses and post-auricular reflexes were sensitive to emotion, but heart rate deceleration and eyeblink reflexes were not. Our findings suggest that although a specific subset of physiological systems can respond to emotional stimuli presented outside of awareness, indicating unconscious processing, consciousness may be characterised by coherent emotional responses across physiological systems.