Géry d’Ydewalle

Detection of symmetry in tachistoscopically presented dot patterns: Effects of multiple axes and skewing

We examined the effects of multiple axes and skewing on the detectability of symmetry in tachistoscopically presented (100-msec) dot patterns to test the role of normal grouping processes based on higher order regularities in element positions. In addition to the first-order regularities of orientational uniformity and midpoint collinearity (Jenkins, 1983), bilateral symmetry (BS) gives rise to second-order relations between two pairs of symmetric elements (represented by correlation quadrangles). We suggest that they allow the regularity (i.e., BS) to emerge simply as a result of the position-based grouping that takes place normally, so that no special symmetry-detection mechanism has to be postulated. In combination with previously investigated variables— number and orientation of axes—we introduced skewing (resulting from orthographic projection of BS) to manipulate the kind and number of higher order regularities. In agreement with our predictions, the data show that the effect of skewing angle (varied at three 15° steps, clockwise and counterclockwise) on the preattentive detectability of symmetry (measured with d’) increases as the number of axes decreases. On the basis of some more specific findings, we suggest that it is not as much the number of correlation quadrangles that determines the saliency of a regularity as it is the degree to which they facilitate or “bootstrap” each other.

Inference suppression and semantic memory retrieval: Every counterexample counts

Reasoning with conditionals involving causal content is known to be affected by retrieval of counterexamples from semantic memory. In this study we examined the characteristics of this search process in everyday conditional reasoning. In Experiment 1 we manipulated the number (zero to four) of explicitly presented counterexamples (alternative causes or disabling conditions) for causal conditionals. In Experiment 2, using a generation pretest, we measured the number of counterexamples participants could retrieve for a set of causal conditionals. One month after the pretest, participants were presented a reasoning task with the same conditionals. The experiments indicated that acceptance of modus ponens linearly decreased with every additionally retrieved disabler, whereas affirmation of the consequent acceptance linearly decreased as a function of the number of retrieved alternatives. Results for denial of the antecedent and modus tollens were less clear. The findings show that the search process does not necessarily stop after retrieval of a single counterexample and that every additional counterexample has an impact on the inference acceptance.

Causal conditional reasoning and semantic memory retrieval: A test of the semantic memory framework

This study tested and refined a framework that proposes a mechanism for retrieving alternative causes and disabling conditions (Cummins, 1995) during reasoning. Experiment 1 examined the relation between different factors affecting retrieval. The test revealed high correlations between the number of possible alternative causes or disabling conditions and their strength of association and plausibility. Experiment 2 explored the hypothesis that due to a more extended search process, conditional inferences would last longer when many alternative causes or disabling conditions were available. Affirmation of the consequent (AC) and modus ponens (MP) latencies showed the hypothesized pattern. Denial of the antecedent (DA) and modus tollens (MT) inferences did not show latency effects. The experiment also identified an effect of the number of disabling conditions on AC and DA acceptance. Experiment 3 measured efficiency of disabler retrieval by a limited time, disabler generation task. As predicted, better disabler retrieval was related to lower acceptance of the MP and MT inferences.

Turbo Pascal timing routines for the IBM microcomputer family

Two Turbo Pascal (versions 3.0 and 4.0) software timers for the IBM microcomputer family are described: one with a 55-msec resolution and another with a 1-msec resolution. Both can be implemented without additional hardware requirements. The 55-msec timer makes use of the system-time-of-day clock; the 1-msec timer is a Turbo Pascal translation of the timer described by Bührer, Sparrer, and Weitkunat (1987). The logic of each timer is shown by a short demonstration program.

Prospective remembering of Korsakoffs and alcoholics as a function of the prospective-memory and on-going tasks

Prospective memory is assumed to rely more on the frontal lobes than retrospective memory. Since Korsakoff patients are known to suffer from a general cerebral atrophy and a frontal lobe atrophy in particular, they are expected to show considerably impaired prospective memory. In Experiment 1, the performance of Korsakoff patients on a semantic prospective-memory task (which was embedded in a perceptual on-going task) was particularly bad in Session 1; in Session 2, the Korsakoff patients improved substantially, to reach the performance level of nonamnesic alcoholics. In Experiment 2, prospective memory of the Korsakoff patients and nonamnesic alcoholics was better when the on-going task was more similar to the prospective-memory task; particularly striking was the much better prospective memory in the semantic prospective-memory task when the on-going task requires a semantic analysis than when the on-going task requires perceptual processing. The findings are in agreement with a task-appropriate processing explanation but also in partial agreement with the attention hypothesis of the instance theory of automaticity. Contrary to the frontal lobe hypothesis, prospective memory of the Korsakoff patients was surprisingly good in several aspects of the two experiments.

The relative contribution of content and context factors on the interpretation of conditionals

Previous research showed that conditional reasoning is affected by the content and the context of the studied problems. In this study, we investigate in detail the relative effect of three factors, namely the number of alternative or disabling reasons, speaker control, and pragmatic type, on the interpretation of conditionals. These factors were subject to prior research, but mostly in a fragmented way. This study indicates that some important nuances must be added to earlier findings. The number of alternatives and disablers, the speaker control, and the pragmatic type of conditional statements all have a considerable effect on how we interpret these sentences and reason with them, but they do not have equal weight. Alternatives/disablers play a significant but very limited role on the interpretation of conditionals, while the influence of speaker control and of pragmatic type is far more imperative.

Brief foveal masking during scene perception.

In the present experiment, participants were exploring line drawings of scenes in the context of an object-decision task, while eye-contingent display changes manipulated the appearance of the foveal part of the image. Foveal information was replaced by an ovoid noise mask for 83 ms, after a preset delay of 15, 35, 60, or 85 ms following the onset of fixations. In control conditions, a red ellipse appeared for 83 ms, centered around the fixation position, after the same delays as in the noise-mask conditions. It was found that scene exploration was hampered especially when foveal masking occurred early during fixations, replicating earlier findings. Furthermore, fixation durations were shown to increase linearly as the mask delay decreased, which validates the fixation duration as a measure of perceptual processing speed.

Is There Any Need for Eye-Movement Recordings During Reasoning?

In experimental research on the psychology of reasoning one mostly uses the nature and frequency of conclusions to reasoning problems as a measure of the cognitive processes involved in reasoning. Less often, researchers use problem solving latencies as an additional measure. We aimed to add more fine-grained measures to the field of reasoning research: namely those obtained by registering eye-movements. At the same time we ventured that those measures might also be obtained without the use of eye-movement registration equipment. By displaying the constituent clauses of reasoning problems contingent upon the movements of a mouse-cursor, we expected to obtain results equally sensitive to the difficulty of making particular inferences. In order to tackle these questions we conducted some studies in which the negations paradigm was applied to the conditional inferences task. Jargon being what it is, we will first explicate what conditional reasoning is about, how conditional reasoning can be investigated with the conditional inferences task and how the negations paradigm is applied to the conditional inferences task. Only then are we in the position to elaborate the hypothesized difficulties in drawing inferences about conditionals with negative constituent clauses; difficulties which were expected to be reflected in eye-movement measures if these are to provide a sensible measures to reasoning processes.

Motivational Issues in Information-Processing Experiments*

The former directors of the Laboratory of Experimental Psychology at the University of Leuven were Albert MICHOTTE who died in 1965 and J.R. NUTTIN who retired in 1980. In recent years, the work at the Laboratory has become more and more concerned with basic and applied research on memory. Together with our collaborators we tried to approach memory from various angles. Work has been carried out on artificial intelligence andmemory (DELHAYE, 1982) and R. PEETERS has begun a research project on autobiographical memory which is still a rather neglected field of research in memory. The purpose of this project is to construct a general framework of the processes involved in autobiographical memory in order to explain why some events of the past history of a person can be retrieved particularly well. One fundamental concern of the research program is to relate episodic and semantic memory in encoding and retrieval processes. Also, some work of CRAIK and LOCKHART (1972) has been done mainly in order to disentangle encoding and retrieval effects from memory scores. The same framework has been applied in the area of consumer psychology (D’YDEWALLE, DELHAYE and GOESSENS, 1983). The subjects made decisions about pictures that induced them to process the advertisements structurally, semantically, or in relation to themselves. The extent of the processing elaboration was also manipulated by requiring decisions on one- or two-attribute questions.

A cognitive neuropsychological approach to false memory: Korsakoff patients and the DRM paradigm

Although false memories have been studied extensively within the field of cognitive psychology, the role of cognitive neuropsychology in false memory research has been rather limited. Therefore, the present article aims at giving an integrated overview of both the neuropsychological study of amnesia and research on false memories. After considering some of the most important predecessors in the study of memory distortions/illusions, a list-learning paradigm designed to elicit and investigate false memories is described (i.e., the DRM paradigm), and theoretical accounts for the phenomenon are provided. Subsequently, the neuropsychological framework is presented, with an emphasis on Korsakoff patients’ performance in the earlier described paradigm. Several experimental manipulations, as well as the results, are discussed and interpreted in the light of both encoding and retrieval factors. (Netherlands Journal of Psychology, 64: 96-111.)