On the function of weak phantasmata in perception: Phenomenological,psychological and neurological clues for the transcendental function of imagination in perception

Weak phantasmata have a decisive and specifically transcendental function in our everyday perception. This paper provides several different arguments for this claim based on evidence from both empirical psychology and phenomenology.I would like to express my gratitude to Bill McKenna for his help with the English text and his critical remarks. This paper was presented in the Cork Roundtable for Philosophy in March 2003, at University College, Cork, and I would like to thank Julia Jansen, Tony O’Connor and the other participants for their constructive critique.     

Coming to terms with risk factors for eating disorders: application of risk terminology and suggestions for a general taxonomy

The aims of the present review are to apply a recent risk factor approach (H. C. Kraemer et al., 1997) to putative risk factors for eating disorders, to order these along a timeline, and to deduce general taxonomic questions. Putative risk factors were classified according to risk factor type, outcome (anorexia nervosa, bulimia nervosa, binge-eating disorder, full vs. partial syndromes), and additional factor characteristics (specificity, potency, need for replication). Few of the putative risk factors were reported to precede the onset of the disorder. Many factors were general risk factors; only few differentiated between the 3 eating disorder syndromes. Common risk factors from longitudinal and cross-sectional studies were gender, ethnicity, early childhood eating and gastrointestinal problems, elevated weight and shape concerns, negative self-evaluation, sexual abuse and other adverse experiences, and general psychiatric morbidity. Suggestions are made for the conceptualization of future risk factor studies.     

Race and information processing in criminal trials: does the defendant's race affect how the facts are evaluated?

Two studies examined whether a criminal defendant's race influences Whites' sensitivity to legally relevant information. In Study 1, prosecution case strength ratings and guilt likelihood ratings were more sensitive to the strength of the defendant's alibi when he was Black than when he was White, if the experimental task was designed to elicit low processing motivation. Under high motivation, participants were equally sensitive to alibi strength, regardless of defendant race. In Study 2, the alibi strength manipulation was replaced with a manipulation of the effectiveness of the district attorney's cross-examination. As predicted, defense case strength ratings were more sensitive to the strength of the prosecutor's cross-examination with a Black defendant than with a White defendant-under low motivation. Under high motivation, sensitivity did not depend on defendant race. These results suggest that a Black defendant can elicit greater sensitivity to legally relevant information than will a White defendant.     

Describing suicidality: an investigation of qualitative SSF responses

Given the incidence and seriousness of suicidality in clinical practice, the need for new and better ways to assess suicide risk is clear. While there are many published assessment instruments in the literature, survey data suggest that these measure are not widely used. One possible explanation is that current quantitatively developed assessment instruments may fail to capture something essential about the suicidal patient's experience. The current exploratory study examined a range of open ended qualitative written responses made by suicidal outpatients to five assessment prompts from the Suicide Status Form (SSF)--psychological pain, press, perturbation, hopelessness, and self-hate. Two different samples of suicidal outpatients seeking treatment, including suicidal college students (n = 119) and active duty U.S. Air Force personnel (n = 33), provided a wide range of written responses to the five SSF prompts. A qualitative coding manual was developed through a step-by-step methodology; two naive coders were trained to use the coding system and were able to sort all the patients' written responses into the content categories with very high interrater reliability (Kappa > .80). Certain written qualitative responses of the patients were more frequent than others, both within and across the five SSF constructs. Among a range of specific exploratory findings, one general finding was that two thirds of the 636 obtained written responses could be reliably categorized under four major content headings: relational (22%), role responsibilities (20%), self (15%), and unpleasant internal states (10%). Theoretical, research, and clinical implications of the methodology and data are discussed.     

Effects of binding in the identification of objects

The binding problem requires a solution at the level of individual neurons, but no definite mechanism has yet be given. Therefore, the neuronal level is as yet inadequate for modeling cognitive processes in which binding plays a crucial role. Moreover, the neuronal level involves too many details that are unlikely to be essential for understanding cognition. A general model of cognitive brain functioning is described in which cognitive tasks are represented in a network of cell assemblies. In the network, binding is functionally defined in a way that is compatible with the neuronal level. A computer simulation of the model clarifies how the binding of location and identity of a set of simultaneously presented letters takes place and how questions about the location and identity of the letters are answered. From the simulation of the task three predictions on the logistics of neural processes are derived: 1. When the cell assembly representing a letter participates in more than one temporary excitation loop, it will reach its critical threshold faster. At the behavioral level this means that as the number of identical letters in the display increases, responses will be faster. 2. In order to answer questions about the location and identity of presented letters cell assemblies representing the target location and the target identity have to become bound to their appropriate values. As a consequence the facilitatory effect of identical letters will be stronger if they involve the target location or the target identity than when identical non-targets are involved. 3. Negative identifications are more dependent on the presentation time of the letters than positive identifications because the excitation loops involved take more time to reach the critical threshold. Therefore, the facilitatory effect of identical letters is stronger when the external activation is relatively strong, i.e., when presentation time of the letters is sufficiently long. The reaction times obtained in three behavioral experiments support these hypotheses. Effects of binding can therefore be predicted on the basis of the general logistics of neural processes, without assumptions about a specific binding mechanism at the neuronal level.     

Actions blind to conceptually overlapping stimuli

Participants are worse at identifying spatial symbols (arrowheads) while performing spatially compatible manual key presses. The present experiments investigated the generality of this blindness effect to response-compatible stimuli. In Experiment 1 a left key press deteriorated the identification of left-pointing arrows, and a right key press deteriorated the perception of right-pointing arrows, independent of the hands used to press the key. Thus the blindness effect is based on codes of the distal response location rather than on the body-intrinsic anatomical connection of the hands. Experiment 2 extended the blindness effect to verbal responses and written position words (left, right, up, down). Vocalizing a position word blinded to directly compatible position words (e.g., left-left), but not to orthogonally compatible position words (e.g., left-down). This result suggests that the use of identical stimulus-response codes, and not the use of saliency-matching but distinct codes, suffices to produce blindness effects. Finally, Experiment 3 extended the blindness phenomenon beyond the spatial domain by demonstrating blindness between saying color words and perceiving color patches. Altogether, the experiments revealed action-induced blindness to be a phenomenon of broad empirical validity occurring whenever action and perception afford simultaneous access to the same conceptual codes.     

Perceiving while acting: action affects perception

In two experiments we studied how motor responses affect stimulus encoding when stimuli and responses are functionally unrelated and merely overlap in time. Such R-S effects across S-R assignments have been reported by Schubö, Aschersleben, and Prinz (2001), who found that stimulus encoding was affected by concurrent response execution in the sense of a contrast (i.e., emphasizing differences). The present study aimed at elucidating the mechanisms underlying this effect. Experiment 1 studied the time course of the R-S effect. Contrast was only obtained for short intertrial intervals (ITIs). With long ITIs contrast turned into assimilation (i.e., emphasizing similarities). Experiment 2 excluded an interpretation of the assimilation effect in terms of motor repetition. Our findings support the notion of a shared representational domain for perception and action control, and suggest that contrast between stimulus and response codes emerges when two S-R assignments compete with each other in perception. When perceptual competition is over, assimilation emerges in memory.