Margit Höfler

Inhibition of return functions within but not across searches

Inhibition of return (IOR) facilitates visual search by discouraging the reinspection of recently processed items. We investigated whether IOR operates across two consecutive searches of the same display for different targets. In Experiment 1, we demonstrated that IOR is present within each of the two searches. In Experiment 2, we found no evidence for IOR across searches. In Experiment 3, we showed that IOR is present across the two searches when the first search is interrupted, suggesting that the completion of the search is what causes the resetting of IOR. We concluded that IOR is a partially flexible process that can be reset when the task completes, but not necessarily when it changes. When resetting occurs, this flexibility ensures that the inhibition of previously visited locations does not interfere with the new search.

Individual versus collaborative learning in a virtual world

E-Learning in general and, specifically, learning in virtual worlds has become more and more popular in recent years. In the present study we investigated whether learning is more successful if students learn in a virtual world individually or collaboratively. We also assessed the motivation of the participants and the usability of the virtual environment. The findings showed a tendency that learning was more successful when participants learned collaboratively than individually. Furthermore, their interest (current motivation) decreased during the learning session when they learned individually and increased when they learned in a group. This experiment shows that, in virtual worlds, collaborative learning seems to be more effective and more engaging than individual learning.

Guidance toward and away from distractors in repeated visual search.

When searching for two targets consecutively in the same display, participants use memory of recently fixated distractors that become the target in the second search to find that target more quickly. Here we ask whether participants are also using memory for fixated distractors that do not become the target. In Experiment 1 we show that search is faster overall in the second search regardless of whether or not the second search target was fixated in the first search. We replicate this effect in Experiment 2 for different display sizes and further show that the effect is a result of the prioritization of locations that are more likely to contain the target. This suggests that representations of the fixated distractor items are retained across the two searches and that these representations can be used flexibly to optimize search performance. Furthermore, this suggests that the short-term memory processes that support search across consecutive searches not only facilitate guidance toward the target but also allow distractors to be excluded from the search process.

Searching the same display twice: Properties of short-term memory in repeated search

Consecutive search for different targets in the same display is supported by a short-term memory mechanism: Distractors that have recently been inspected in the first search are found more quickly in the second search when they become the target (Exp. 1). Here, we investigated the properties of this memory process. We found that this recency advantage is robust to a delay between the two searches (Exp. 2) and that it is only slightly disrupted by an interference task between the two searches (Exp. 3). Introducing a concurrent secondary task (Exp. 4) showed that the memory representations formed in the first search are based on identity as well as location information. Together, these findings show that the short-term memory that supports repeated visual search stores a complex combination of item identity and location that is robust to disruption by either time or interference.

Modern education and its background in cognitive psychology: Automated question creation and eye movements

In modern education, the automatic generation of test items out of texts becomes increasingly important. We have recently presented an enhanced automatic question creator (EAQC) that is able to extract the most relevant concepts out of a text and to create test items based on these concepts. Furthermore, from eye-movement research it is known that learners fixate potentially relevant information longer and more often. In the present study, we investigated whether the measurement of (individual) relevance of EAQC-concepts is related to the frequency and duration of fixations from learners when they read a text, learn it or manually extract concepts out of it. Overall, results showed a non-significant tendency that participants needed more fixations when learning the text as compared to when reading it or extracting concepts. Saccade lengths were reliably longer when participants extracted concepts than when they read them; no other differences were found. How long and how often a concept was fixated did not vary with the subjective relevance of the concept according to participants ratings. Future research is therefore necessary to investigate a possible relationship between eye movement behavior and automated concept extraction.

Neuronal interactions in areas of spatial attention reflect avoidance of disgust, but orienting to danger

For survival, it is necessary to attend quickly towards dangerous objects, but to turn away from something that is disgusting. We tested whether fear and disgust sounds direct spatial attention differently. Using fMRI, a sound cue (disgust, fear or neutral) was presented to the left or right ear. The cue was followed by a visual target (a small arrow) which was located on the same (valid) or opposite (invalid) side as the cue. Participants were required to decide whether the arrow pointed up- or downwards while ignoring the sound cue. Behaviorally, responses were faster for invalid compared to valid targets when cued by disgust, whereas the opposite pattern was observed for targets after fearful and neutral sound cues. During target presentation, activity in the visual cortex and IPL increased for targets invalidly cued with disgust, but for targets validly cued with fear which indicated a general modulation of activation due to attention. For the TPJ, an interaction in the opposite direction was observed, consistent with its role in detecting targets at unattended positions and in relocating attention. As a whole our results indicate that a disgusting sound directs spatial attention away from its location, in contrast to fearful and neutral sounds.

The consequence of a limited-capacity short-term memory on repeated visual search

ABSTRACT When participants search the same letter display repeatedly for different targets we might expect performance to improve on each subsequent search as they memorize characteristics of the display. However, here we find that search performance improved from a first search to a second search but not for a third search of the same display. This is predicted by a simple model that supports search with only a limited capacity short-term memory for items in the display. To support this model we show that a short-term memory recency effect is present in both the second and the third search. The magnitude of these effects is the same in both searches and as a result there is no additional benefit from the second to the third search.

Target probability modulates fixation-related potentials in visual search

This study investigated the influence of target probability on the neural response to target detection in free viewing visual search. Participants were asked to indicate the number of targets (one or two) among distractors in a visual search task while EEG and eye movements were co-registered. Target probability was manipulated by varying the set size of the displays between 10, 22, and 30 items. Fixation-related potentials time-locked to first target fixations revealed a pronounced P300 at the centro-parietal cortex with larger amplitudes for set sizes 22 and 30 than for set size 10. With increasing set size, more distractor fixations preceded the detection of the target, resulting in a decreased target probability and, consequently, a larger P300. For distractors, no increase of P300 amplitude with set size was observed. The findings suggest that set size specifically affects target but not distractor processing in overt serial visual search.