Perception and its neuronal mechanisms

A classic view of the relation between sensorineural activity and perception has assumed that the former is somehow transformed into the latter at some locus in the brain. This notion conflicts with the modern view that the activity of the nervous system is restricted to transmitting and processing information. It is suggested that the conflict may be resolved by considering perception as reflective activity rather than passive reception. This cognitive process entails information about the perceiving self and the general context and not merely the stimulus input. Some aspects of perception can be related to neuronal mechanisms and even to neuronal activity at specific loci. How is this done? By identifying the characteristics of the perceptual process and finding a necessary and sufficient neuronal mechanism that receives information about the stimulus input and can perform the implied computation. Examples are taken from the study of visual development in human infants.     

Believability and syllogistic reasoning

In this paper we investigate the locus of believability effects in syllogistic reasoning. We identify three points in the reasoning process at which such effects could occur: the initial interpretation of premises, the examination of alternative representations of them (in all of which any valid conclusion must be true), and the "filtering" of putative conclusions. The effect of beliefs at the first of these loci is well established. In this paper we report three experiments that examine whether beliefs have an effect at the other two loci. In experiments 1 and 2 subjects drew their own conclusions from syllogisms that suggested believable or unbelievable ones. In the third experiment they evaluated conclusions that were presented to them. The data show that beliefs both affect the examination of alternative models and act as a filter on putative conclusions. We conclude by showing how some types of problem and some problem contents make the existence of alternative models more obvious than others.     

The development of separability in visual perception

Under conditions that do not allow focused attention, reports of illusory conjunctions (i.e. errors that wrongly recombine the features of different objects) constitute evidence of the separate registering of features at an early processing level. The occurrence of illusory conjunctions was used to determine whether there is preattentive analysis of component dimensions (colour and form) and of parts of shapes (triangles and arrows) in young children aged 5 to 8 years. Evidence of preattentive analysis was found, even for the youngest children, for colour and form but not for parts of shapes. Although developmental effects hardly reached significance, inspection of abilities assumed to affect the illusory conjunctions phenomenon suggests that at the preattentive stage children can integrate spatially separate segments but lack the capacity to fully analyse connected segments.     

Dynamic organization of intersensory function

Issues related to infant intersensory functioning are reviewed. The argument is offered that limitations of sensory inputs during early stages of development are necessary and provide structure and organization which determine behavioural characteristics at later stages. It is also suggested that infant organisms respond to the intensity of stimulation rather than organizational characteristics and that this is responsible for the form of sensory equivalence apparent during early development. A scheme for the investigation of sources of intersensory organization is presented which involves a prospective analysis of how consideration of the times of onset of sensory functions helps us to understand intra- and intersensory development. The advantages of this experimental approach are outlined.     

The composition of imaginal transformations

Three experiments examine the performance of composite imaginal spatial transformations using tasks in which people perform pairs of distinct imaginal transformations either in close succession or simultaneously. The principal aim of the investigation is to determine, for both modes of composition, whether imaginal transformations combine interactively or noninteractively to determine the temporal course of imaging performance. Specifically, does the time to imagine a given composite transformation reflect the independent contributions of its component transformations, or do component transformations have different effects within different composites? Results obtained under a number of distinct task conditions are most consistent with the proposal of noninteractive composition. However, the temporal effects of particular imaginal transformations are neither consistent nor readily predictable across different task conditions. Implications of these results for analogue-spatial models, task demand, and procedural accounts of imaging are discussed.     

The psychology of knights and knaves

Knight-knave brain teasers are about a realm in which some people, knights, tell only truths, whereas all others, knaves, tell only lies. For example, suppose person A says, "I am a knight and B is a knight," and person B says, "A is a knave." Is A a knight or a knave? Is B a knight or a knave? In a pilot study, we asked subjects to think aloud while solving problems like these. Their statements suggested that they were making assumptions about the knight/knave status of the characters and drawing deductive inferences from these assumptions to test their consistency. This encouraged us to model the process by means of a simulation based on an earlier natural-deduction theory of reasoning. The model contains a set of deduction rules in the form of productions and a working memory that holds a proof of the correct answer. The greater the number of steps (assumptions and inferences) in the proof, the greater the predicted difficulty of the puzzle. The experiments reported here confirmed this prediction by showing that subjects were more likely to make mistakes (Experiment 1) and take longer to solve (Experiment 2) puzzles associated with a larger number of proof steps.     

Neuronal models of cognitive functions

Understanding the neural bases of cognition has become a scientifically tractable problem, and neurally plausible models are proposed to establish a causal link between biological structure and cognitive function. To this end, levels of organization have to be defined within the functional architecture of neuronal systems. Transitions from any one of these interacting levels to the next are viewed in an evolutionary perspective. They are assumed to involve: (1) the production of multiple transient variations and (2) the selection of some of them by higher levels via the interaction with the outside world. The time-scale of these "evolutions" is expected to differ from one level to the other. In the course of development and in the adult this internal evolution is epigenetic and does not require alteration of the structure of the genome. A selective stabilization (and elimination) of synaptic connections by spontaneous and/or evoked activity in developing neuronal networks is postulated to contribute to the shaping of the adult connectivity within an envelope of genetically encoded forms. At a higher level, models of mental representations, as states of activity of defined populations of neurons, are discussed in terms of statistical physics, and their storage is viewed as a process of selection among variable and transient pre-representations. Theoretical models illustrate that cognitive functions such as short-term memory and handling of temporal sequences may be constrained by "microscopic" physical parameters. Finally, speculations are offered about plausible neuronal models and selectionist implementations of intentions.     

Hypothesizing and evidence-gathering: the nexus of understanding

Prior discussion of hypothesizing as a session "guideline" has not fully clarified the derivation of hypotheses. Reviewing relevant philosophy of science literature, the authors develop the notions of evidence and evidence-gathering in systemic family therapy. The authors claim evidence-gathering and hypothesizing are interdependent, reciprocal elements of scientific understanding. The structure of evidence is described along with practical and qualitative rules for collecting and using evidence. This model is applied to a case example illustrating the logic of clinical process. Implications are discussed for family therapy training and supervision.     

A sermon from hell: Toward a theology of loneliness

Loneliness as part of the human condition is first explored from an experiential-philosophical perspective. A biblical survey suggests loneliness is normative to the faith experience and may portray a more realistic religiosity. Desert imagery in Scripture indicates a strong association among solitude, spiritual development, and potential dangers of spiritual deception. God's not yet-ness-itself a cause of existential loneliness—is paradoxically the way in which communion with God functions in the here and now. The creative use of solitude may enhance social, psychological, and spiritual well-being, and provide a way to theologize about personal isolation and disorientation.He is also editor of theHarding Journal of Religion and Psychiatry.     

Religious celibacy from the celibate's point of view

What do celibates consider the adaptive and maladaptive aspects of their celibate religious lifestyle? What role has celibacy played in understanding the differences between those who persevere and those who choose to resign from celibate religious life and/or ordained ministry? Using data from extensive interviews, this exploratory study begins to focus some of the perceived effects of celibacy upon personal development for both those who persevere in celibate religious life and those who resign.