A Poetics of Psychological Explanation

Intentional, 'commonsense,' or 'folk' psychology is, as Jerry Fodor has remarked, ubiquitous. Explanations of what we say and do in terms of our reasons for acting are the stock in trade of intentional psychology. But there is a question whether explanations in terms of reasons are properly explanatory. Donald Davidson and Daniel Dennett, to name two, have defended intentional psychology and its reason-explanations. Still, many philosophers – including Fodor, Davidson and Dennett – fail to pay due attention to the narrative basis of such agent-centered accounts of action. In this paper, I argue that psychological explanation is an agent-centered, narrative-based interpretive practice. To make my case, I present a poetics of psychological explanation: seven elements which collectively describe what makes psychological explanations work. Narrative form allows us to represent the temporal arc of agents' actions – as well as the temporal arc of their reasoning about their actions, both prospective and retrospective. It allows us to negotiate between the canonical and the exceptional in human experience, and thus to account for actions that strike us as puzzling or unusual – whether the puzzle originates in our suboptimal understanding or the agent's suboptimal reasoning. And it allows us to juxtapose different perspectives on any action. Such juxtapositioning gives us a mechanism for coming to see how an action that strikes us as misguided might have been construed by the agent as reasonable given her understanding of her circumstances. After establishing the seven elements of the poetics, I address the objection that narrative-based accounts of intentional action are not properly explanatory.     

On the Poverty of Scientism, or: The Ineluctable Roughness of Rationality

If there is one rationality there must be a plurality of them. This conclusion follows, I argue, partly from the extreme and ineradicable vagueness of the fundamental concepts that every would-be rational explanation must presuppose. Logicistic/scientistic assaults on this vagueness are doomed to fail partly because they are unable to acknowledge the imaginative dimension of rational thought. Being limited to the play of "outward appearances," scientific investigations are also dependent on "inward imaginings" on their speculative side. The upshot is that schools of philosophy should be characterized by the kind of imaginary they adopt rather than by their logics. In which case, every attempt to get and tell something right about the world is bound to incorporate mythopoeic elements in its explanations.     

Is it worth generating rules from neural network ensembles?

Although many authors generated comprehensible models from individual networks, much less work has been done in the explanation of ensembles. DIMLP is a special neural network model from which rules are generated at the level of a single network and also at the level of an ensemble of networks. We applied ensembles of 25 DIMLP networks to several datasets of the public domain and a classification problem related to post-translational modifications of proteins. For the classification problems of the public domain, the average predictive accuracy of rulesets extracted from ensembles of neural networks was significantly better than the average predictive accuracy of rulesets generated from ensembles of decision trees. By varying the architectures of DIMLP networks we found that the average predictive accuracy of rules, as well as their complexity were quite stable. The comparison to other rule extraction techniques applied to neural networks showed that rules generated from DIMLP ensembles gave very good results. In the last problem related to bioinformatics, the best result obtained by ensembles of DIMLP networks was also significantly better than the best result obtained by ensembles of decision trees. Thus, although neural networks take much longer to train than decision trees and also rules are generated at a greater computational cost (however, still polynomial), at least for several classification problems it was worth using neural network ensembles, as extracted rules were more accurate, on average. The DIMLP software is available for PC-Linux under http://us.expasy.org/people/Guido.Bologna.html.     

The levels of perceptual processing and the neural correlates of increasing subjective visibility

According to the levels-of-processing hypothesis, transitions from unconscious to conscious perception may depend on stimulus processing level, with more gradual changes for low-level stimuli and more dichotomous changes for high-level stimuli. In an event-related fMRI study we explored this hypothesis using a visual backward masking procedure. Task requirements manipulated level of processing. Participants reported the magnitude of the target digit in the high-level task, its color in the low-level task, and rated subjective visibility of stimuli using the Perceptual Awareness Scale. Intermediate stimulus visibility was reported more frequently in the low-level task, confirming prior behavioral results. Visible targets recruited insulo-fronto-parietal regions in both tasks. Task effects were observed in visual areas, with higher activity in the low-level task across all visibility levels. Thus, the influence of level of processing on conscious perception may be mediated by attentional modulation of activity in regions representing features of consciously experienced stimuli.     

Identification and integration of sensory modalities: Neural basis and relation to consciousness

A key question in studying consciousness is how neural operations in the brain can identify streams of sensory input as belonging to distinct modalities, which contributes to the representation of qualitatively different experiences. The basis for identification of modalities is proposed to be constituted by self-organized comparative operations across a network of unimodal and multimodal sensory areas. However, such network interactions alone cannot answer the question how sensory feature detectors collectively account for an integrated, yet phenomenally differentiated experiential content. This problem turns out to be different from, although related to, the binding problem. It is proposed that the neural correlate of an enriched, multimodal experience is constituted by the attractor state of a dynamic associative network. Within this network, unimodal and multimodal sensory maps continuously interact to influence each other’s attractor state, so that a feature change in one modality results in a fast re-coding of feature information in another modality. In this scheme, feature detection is coded by firing-rate, whereas firing phase codes relational aspects.     

Influence of dorsal hippocampal lesions and MMP inhibitors on spontaneous recovery following a habituation/classical conditioning head–shake task

The present investigation combined a classical conditioning paradigm with a head–shake response (HSR) habituation task in order to evaluate the importance of dorsal hippocampal neural plasticity to spontaneous recovery. In the first experiment animals exhibited rapid HSR habituation (air stimulus to the ear) and an 85% level of spontaneous recovery following a 24 h inter-session interval. The addition of a brief tone prior to the air stimulus produced a similar pattern of habituation during the first session, but the level of spontaneous recovery was reduced (44%) during Session II. In a second experiment dorsal hippocampal lesioned rats placed on this tone/HSR paradigm responded with an 87% level of spontaneous recovery during Session II; while neocortex lesioned control rats indicated significantly reduced levels of spontaneous recovery (55%). In a third experiment bilateral injections of a general MMP inhibitor, FN-439, into the dorsal hippocampus resulted in high levels of spontaneous recovery (81%); while control rats injected with artificial cerebrospinal fluid displayed a significant attenuation of spontaneous recovery (45%). Finally, animals bilaterally injected with a specific MMP-3 inhibitor into the dorsal hippocampus indicated very similar results to those obtained following FN-439 injection. These findings indicate that animals prepared with dorsal hippocampal lesions, or injections with an MMP inhibitor, revealed an impaired association between the tone and air stimulus thus maximum spontaneous recovery was present 24 h later. Thus, it appears that the dorsal hippocampus influences habituation by conserving responses and reducing spontaneous recovery when a temporally contingent signaling cue is present.     

Perception with compensatory devices: from sensory substitution to sensorimotor extension

Sensory substitution devices provide through an unusual sensory modality (the substituting modality, e.g., audition) access to features of the world that are normally accessed through another sensory modality (the substituted modality, e.g., vision). In this article, we address the question of which sensory modality the acquired perception belongs to. We have recourse to the four traditional criteria that have been used to define sensory modalities: sensory organ, stimuli, properties, and qualitative experience ( Grice, 1962 ), to which we have added the criteria of behavioral equivalence ( Morgan, 1977 ), dedication ( Keeley, 2002 ), and sensorimotor equivalence ( O'Regan & Noë, 2001 ). We discuss which of them are fulfilled by perception through sensory substitution devices and whether this favors the view that perception belongs to the substituting or to the substituted modality. Though the application of a number of criteria might be taken to point to the conclusion that perception with a sensory substitution device belongs to the substituted modality, we argue that the evidence leads to an alternative view on sensory substitution. According to this view, the experience after sensory substitution is a transformation, extension, or augmentation of our perceptual capacities, rather than being something equivalent or reducible to an already existing sensory modality. We develop this view by comparing sensory substitution devices to other "mind-enhancing tools" such as pen and paper, sketchpads, or calculators. An analysis of sensory substitution in terms of mind-enhancing tools unveils it as a thoroughly transforming perceptual experience and as giving rise to a novel form of perceptual interaction with the environment.     

A neural model of how the brain computes heading from optic flow in realistic scenes

Visually-based navigation is a key competence during spatial cognition. Animals avoid obstacles and approach goals in novel cluttered environments using optic flow to compute heading with respect to the environment. Most navigation models try either explain data, or to demonstrate navigational competence in real-world environments without regard to behavioral and neural substrates. The current article develops a model that does both. The ViSTARS neural model describes interactions among neurons in the primate magnocellular pathway, including V1, MT⁺, and MSTd. Model outputs are quantitatively similar to human heading data in response to complex natural scenes. The model estimates heading to within 1.5° in random dot or photo-realistically rendered scenes, and within 3° in video streams from driving in real-world environments. Simulated rotations of less than 1°/s do not affect heading estimates, but faster simulated rotation rates do, as in humans. The model is part of a larger navigational system that identifies and tracks objects while navigating in cluttered environments.     

Age-related differences in the involvement of the prefrontal cortex in attentional control

We investigated the relative involvement of cortical regions supporting attentional control in older and younger adults during performance on a modified version of the Stroop task. Participants were exposed to two different types of incongruent trials. One of these, an incongruent-ineligible condition, produces conflict at the non-response level, while the second, an incongruent-eligible condition, produces conflict at both non-response and response levels of information processing. Greater attentional control is needed to perform the incongruent-eligible condition compared to other conditions. We examined the cortical recruitment associated with this task in an event-related functional magnetic resonance imaging paradigm in 25 older and 25 younger adults. Our results indicated that while younger adults demonstrated an increase in the activation of cortical regions responsible for maintaining attentional control in response to increased levels of conflict, such sensitivity and flexibility of the cortical regions to increased attentional control demands was absent in older adults. These results suggest a limitation in older adults’ capabilities for flexibly recruiting the attentional network in response to increasing attentional demands.