Modeling geometric–optical illusions: A variational approach

Visual distortions of perceived lengths, angles, or forms, are generally known as “geometric–optical illusions” (goi). In the present paper we focus on a class of gois where the distortion of a straight line segment (the “target” stimulus) is induced by an array of non-intersecting curvilinear elements (“context” stimulus). Assuming local target–context interactions in a vector field representation of the context, we propose to model the perceptual distortion of the target as the solution to a minimization problem in the calculus of variations. We discuss properties of the solutions and reproduction of the respective form of the perceptual distortion for several types of contexts. Moreover, we draw a connection between the interactionist model of gois and Riemannian geometry: the context stimulus is understood as perturbing the geometry of the visual field from which the illusory distortion naturally arises. The approach is illustrated by data from a psychophysical experiment with nine subjects and six different contexts.     

Die Möglichkeit einer objektiven Messung der Stärke von Gefühlen

Zusammenfassung Es war das Ziel, ein Maß für die Stärke von Gefühlen aus einem ihrer physischen Korrelate, der sog. psychogalvanischen Reaktion, zu gewinnen. Zu diesem Zweck wurden Vergleichsurteile über die Gefühlsbetonung von Reizwortpaaren den durch die Darbietung der Wörter ausgelösten Hautreaktionen zugeordnet. Mit den Maßzahlen wurden eine logarithmische Transformation und eine Quadratwurzeltransformation vorgenommen. Die Auswertung erfolgte jeweils gemäß dem Skalierungsverfahren für Vergleichsurteile. Es zeigte sich, daß die auf Grund der Quadratwurzeltransformation erhaltenen Skalenwerte für die Gefühlsstärke in voll befriedigender Weise durch eine Gerade angenähert werden können, während dies mit der logarithmischen Transformation weniger gut gelingt.Um aus der gefundenen Intervallskala der Gefühlsstärke eine Verhältnisskala zu erhalten, wurde die Gefühlsschwelle der galvanischen Hautreaktion zu bestimmen versucht. Es ergab sich, daß der Schwellenwert der emotionalen Veränderung bei der Größe 0 der Hautwiderstandsänderung liegt. Es folgt daraus, daß die Stärke eines Gefühls als der Quadratwurzel der relativen Widerstandsänderung proportional anzunehmen ist.Dieses Ergebnis wird durch ein Anwendungsbeispiel veranschaulicht.     

Implicit and explicit memory without awareness

Summary Three experiments are reported which investigate the conscious status of subjects during an implicit-memory test. In all experiments the subjects either named each visually presented target item or generated each item from an anagram in a first phase of incidental learning. In a second phase, they were either given a visual word-stem completion task as an implicit-memory test or given a recognition task (Experiment 1), or a cued-recall task (Experiments 2 and 3) as explicit-memory tests. Finally, in a third phase the subjects were required to make decisions about the input status (i. e., they had to decide whether the item was present in the first phase) as well as about the output status of information (i. e., they had to decide whether the item had been completed, recognized or recalled in the second phase). A generation effect (i. e., generated items were remembered better than named items) was evident in the recognition and recall data, but only for items whose recognition or recall was accompanied by conscious recollection of their previous occurrence in the study list. Judgments about the input status were more precise, given that items had been consciously recognized or recalled rather than completed. The same pattern of findings was observed for judgments about the output status. The results are interpreted as evidence that subjects in implicit-memory tests are less aware of the fact that some of their productions are relevant to prior experiences. In addition, they are less aware of the fact that they are retrieving information from their memories. However, the same state of nonawareness may be present in explicit-memory tests, as was revealed by the performance of subjects on those items whose recognition or recall was not accompanied by conscious recollection.     

Hegel on Kant's Analytic–Synthetic Distinction

In this paper, I argue, first, that Hegel defended a version of the analytic/synthetic distinction—that, indeed, his version of the distinction deserves to be called Kantian. For both Kant and Hegel, the analytic/synthetic distinction can be explained in terms of the discursive character of cognition: insofar as our cognition is discursive, its most basic form can be articulated in terms of a genus/species tree. The structure of that tree elucidates the distinction between analytic and synthetic judgments. Second, I argue that Hegel has an interesting and so far unexplored argument for the analytic/synthetic distinction: Hegel argues that the systematic relationship between concepts expressed in a genus/species tree can only be expressed through synthetic judgments. Third and finally, I explore some of the implications that the arguments in the first two parts of the essay have for understanding the way in which Hegel differs from Kant. I argue that Hegel accepts Kant's point that discursive cognition cannot be used to cognize the absolute. However, Hegel thinks that we can, nevertheless, cognize the absolute. I explore the character of this non‐discursive cognition and argue that we can understand Hegel's glosses on this form of cognition—as simultaneously analytic and synthetic and as having a circular structure—through contrasting it with his account of discursive cognition. As a consequence, I argue that we must give up on attempts to understand ‘the dialectical method’ and ‘speculative cognition’ on the model of discursive cognition.     

Exploring the relationship between religious fundamentalism,life satisfaction,and meaning in life

This study explored the relationship between life satisfaction, meaning in life, and religious fundamentalism among 420 participants (28.8% male, 88.4% African, 8.4% White) residing in the Gauteng province of South Africa. A cross-sectional quantitative survey design was followed. Data were collected using the Meaning in Life questionnaire and the Satisfaction with Life scale, and analysed by means of latent variable modelling. Results indicated that meaning in life acted as a mediator between religious fundamentalism and life satisfaction. This suggests that in some cases, fundamentalist religious attitudes might be adaptive in that it provides its adherents with a clear framework of meaning and definite answers to life's existential uncertainties.     

The influence of emotion type,social value orientation and processing focus on approach-avoidance tendencies to negative dynamic facial expressions

Facial expressions of anger and fear have been seen to elicit avoidance behavior in the perceiver due to their negative valence. However, recent research uncovered discrepancies regarding these immediate motivational implications of fear and anger, suggesting that not all negative emotions trigger avoidance to a comparable extent. To clarify those discrepancies, we considered recent theoretical and methodological advances, and investigated the role of social preferences and processing focus on approach-avoidance tendencies (AAT) to negative facial expressions. We exposed participants to dynamic facial expressions of anger, disgust, fear, or sadness, while they processed either the emotional expression or the gender of the faces. AATs were assessed by reaction times of lever movements, and by posture changes via head-tracking. We found that—relative to angry faces-, fearful and sad faces triggered more approach, with a larger difference between fear and anger in prosocial compared to individualistic participants. Interestingly, these findings are in line with a recently developed concern hypothesis, suggesting that—relative to other negative expressions—expressions of distress may facilitate approach, especially in participants with prosocial preferences.     

Disentangling the adult attention-deficit hyperactivity disorder endophenotype: parametric measurement of attention

Attention deficit hyperactivity disorder (ADHD) persists frequently into adulthood. The decomposition of endophenotypes by means of experimental neuro-cognitive assessment has the potential to improve diagnostic assessment, evaluation of treatment response, and disentanglement of genetic and environmental influences. We assessed four parameters of attentional capacity and selectivity derived from simple psychophysical tasks (verbal report of briefly presented letter displays) and based on a "theory of visual attention." These parameters are mathematically independent, quantitative measures, and previous studies have shown that they are highly sensitive for subtle attention deficits. Potential reductions of attentional capacity, that is, of perceptual processing speed and working memory storage capacity, were assessed with a whole report paradigm. Furthermore, possible pathologies of attentional selectivity, that is, selection of task-relevant information and bias in the spatial distribution of attention, were measured with a partial report paradigm. A group of 30 unmedicated adult ADHD patients and a group of 30 demographically matched healthy controls were tested. ADHD patients showed significant reductions of working memory storage capacity of a moderate to large effect size. Perceptual processing speed, task-based, and spatial selection were unaffected. The results imply a working memory deficit as an important source of behavioral impairments. The theory of visual attention parameter working memory storage capacity might constitute a quantifiable and testable endophenotype of ADHD.     

Has someone moved my plate? The immediate and persistent effects of object location changes on gaze allocation during natural scene viewing

In this study, we investigated the immediate and persisting effects of object location changes on gaze control during scene viewing. Participants repeatedly inspected a randomized set of naturalistic scenes for later questioning. On the seventh presentation, an object was shown at a new location, whereas the change was reversed for all subsequent presentations of the scene. We tested whether deviations from stored scene representations would modify eye movements to the changed regions and whether these effects would persist. We found that changed objects were looked at longer and more often, regardless of change reportability. These effects were most pronounced immediately after the change occurred and quickly leveled off once a scene remained unchanged. However, participants continued to perform short validation checks to changed scene regions, which implies a persistent modulation of eye movement control beyond the occurrence of object location changes.     

Coordination of a discrete response with periodic finger tapping: additional experimental aspects for a subtle mechanism

The authors investigated the coordination of periodic right-hand tapping with single stimulus-evoked discrete lefthand taps to check for task interactions and a possible relationship between phase resetting (see tapping literature; e.g., J. Yamanishi, M. Kawato, & R. Suzuki, 1979) and phase entrainment (see tremor literature; e.g., R. J. Elble, C. Higgins, & L. Hughes, 1994). The experimental paradigm employs a dual-task condition as used by K. Yoshino, K. Takagi, T. Nomura, S. Sato, and M. Tonoike (2002), and it includes normal tapping and isometric tapping with the authors recording finger positions and ground contact forces. Four different types of coordination schemes were observed in tapping behavior: marginal tapping interaction (MTI), periodic tap retardation (PTR), periodic tap hastening (PTH), and discrete tap entrainment (DTE); MTI and PTR correspond to the phase-resetting effect for the coordination of periodic tapping with single discrete taps. The novel aspect of the study described in this article includes the impact of the periodic tapping on the discrete tap timing and the hastening of the periodic tapping due to the discrete tap behaviors resulting in a synchronized execution of the two concurrent tapping tasks. All participants showed a dominant tapping behavior, but they all used the other nondominant forms of the four reported coordination schemes in some trials too, which reflects possible constraints of the sensorimotor system in handling two competing tasks.