S21RS SGCR No. 35 (LGBTQ+ Caucus)

A Concurrent Resolution To establish the LSU Student Government LGBTQ+ Caucu

Time course of information processing in visual and haptic object classification

Vision identifies objects rapidly and efficiently. In contrast, object recognition by touch is much slower. Furthermore, haptics usually serially accumulates information from different parts of objects, whereas vision typically processes object information in parallel. Is haptic object identification slower simply due to sequential information acquisition and the resulting memory load or due to more fundamental processing differences between the senses? To compare the time course of visual and haptic object recognition, we slowed visual processing using a novel, restricted viewing technique. In an electroencephalographic (EEG) experiment, participants discriminated familiar, nameable from unfamiliar, unnamable objects both visually and haptically. Analyses focused on the evoked and total fronto-central theta-band (5–7 Hz; a marker of working memory) and the occipital upper alpha-band (10–12 Hz; a marker of perceptual processing) locked to the onset of classification. Decreases in total upper alpha-band activity for haptic identification of objects indicate a likely processing role of multisensory extrastriate areas. Long-latency modulations of alpha-band activity differentiated between familiar and unfamiliar objects in haptics but not in vision. In contrast, theta-band activity showed a general increase over time for the slowed-down visual recognition task only. We conclude that haptic object recognition relies on common representations with vision but also that there are fundamental differences between the senses that do not merely arise from differences in their speed of processing

Time course of information processing in visual and haptic object classification

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Size-sensitive perceptual representations underlie visual and haptic object recognition.

A variety of similarities between visual and haptic object recognition suggests that the two modalities may share common representations. However, it is unclear whether such common representations preserve low-level perceptual features or whether transfer between vision and haptics is mediated by high-level, abstract representations. Two experiments used a sequential shape-matching task to examine the effects of size changes on unimodal and crossmodal visual and haptic object recognition. Participants felt or saw 3D plastic models of familiar objects. The two objects presented on a trial were either the same size or different sizes and were the same shape or different but similar shapes. Participants were told to ignore size changes and to match on shape alone. In Experiment 1, size changes on same-shape trials impaired performance similarly for both visual-to-visual and haptic-to-haptic shape matching. In Experiment 2, size changes impaired performance on both visual-to-haptic and haptic-to-visual shape matching and there was no interaction between the cost of size changes and direction of transfer. Together the unimodal and crossmodal matching results suggest that the same, size-specific perceptual representations underlie both visual and haptic object recognition, and indicate that crossmodal memory for objects must be at least partly based on common perceptual representations

The effects of temporal delay and orientation on haptic object recognition

We examined the effects of interstimulus interval (ISI) and orientation changes on the haptic recognition of novel objects, using a sequential shape-matching task. The stimuli consisted of 36 wedge-shaped plastic objects that varied along two shape dimensions (hole/bump and dip/ridge). Two objects were presented at either the same orientation or a different orientation, separated by either a short (3-sec) ISI or a long (15-sec) ISI. In separate conditions, ISI was blocked or randomly intermixed. Participants ignored orientation changes and matched on shape alone. Although performance was better in the mixed condition, there were no other differences between conditions. There was no decline in performance at the long ISI. There were similar, marginally significant benefits to same-orientation matching for short and long ISIs. The results suggest that the perceptual object representations activated from haptic inputs are both stable, being maintained for at least 15 sec, and orientation sensitive. © 2010 The Psychonomic Society, Inc

Emotional content overrides spatial attention

Spatial attention is our capacity to attend to or ignore particular regions of our spatial environment. However, some classes of stimuli may be able to override our efforts to ignore them. Here we assessed the relationship between involuntary attentional capture with emotional images and spatial attention at early stages of perceptual processing. Multiple scenes of unpleasant and neutral content were displayed in rapid serial visual presentation (RSVP) streams that elicited the steady-state visual evoked potential (SSVEP), a neural marker of selective attention at early visual areas. In a spatial cueing task, participants were cued to covertly attend to RSVP streams presented at 4 and 6 Hz presentation rates in the left and right visual hemifields. The task was to detect square targets occasionally displayed within the image streams, responding only to those appearing on the cued side. The RSVP streams were always neutral pictures in one visual hemifield but would unpredictably switch from neutral to aversive content in the other visual hemifield. We found that SSVEP amplitude was consistently modulated by a change in emotional valence of image streams, regardless of whether the change in content occurred in the attended or unattended spatial location, reflecting an automatic sensory amplification for affective stimuli. The present data provide further evidence in support that emotional images can attract visual processing resources independently of spatial attention allocation, and are consistent with sustained sensory facilitation of early visual areas through re-entrant feedback projections from higher-order cortical areas involved in the extraction of affective information

Low-level and high-level modulations of fixational saccades and high frequency oscillatory brain activity in a visual object classification task

Until recently induced gamma-band activity (GBA) was considered a neural marker of cortical object representation. However, induced GBA in the electroencephalogram (EEG) is susceptible to artifacts caused by miniature fixational saccades. Recent studies have demonstrated that fixational saccades also reflect high-level representational processes. Do high-level as opposed to low-level factors influence fixational saccades? What is the effect of these factors on artifact-free GBA? To investigate this, we conducted separate eye tracking and EEG experiments using identical designs. Participants classified line drawings as objects or non-objects. To introduce low-level differences, contours were defined along different directions in cardinal color space: S-cone-isolating, intermediate isoluminant, or a full-color stimulus, the latter containing an additional achromatic component. Prior to the classification task, object discrimination thresholds were measured and stimuli were scaled to matching suprathreshold levels for each participant. In both experiments, behavioral performance was best for full-color stimuli and worst for S-cone isolating stimuli. Saccade rates 200–700 ms after stimulus onset were modulated independently by low and high-level factors, being higher for full-color stimuli than for S-cone isolating stimuli and higher for objects. Low-amplitude evoked GBA and total GBA were observed in very few conditions, showing that paradigms with isoluminant stimuli may not be ideal for eliciting such responses. We conclude that cortical loops involved in the processing of objects are preferentially excited by stimuli that contain achromatic information. Their activation can lead to relatively early exploratory eye movements even for foveally-presented stimuli

Do left and right matter for haptic recognition of familiar objects?

Two experiments were carried out to examine the effects of dominant right versus non-dominant left exploration hand and left versus right object orientation on haptic recognition of familiar objects. In experiment 1, participants named 48 familiar objects in two blocks. There was no dominant-hand advantage to naming objects haptically and there was no interaction between exploration hand and object orientation. Furthermore, priming of naming was not reduced by changes of either object orientation or exploration hand. To test whether these results were attributable to a failure to encode object orientation and exploration hand, experiment 2 replicated experiment 1 except that the unexpected task in the second block was to decide whether either exploration hand or object orientation had changed relative to the initial naming block. Performance on both tasks was above chance, demonstrating that this information had been encoded into long-term haptic representations following the initial block of naming. Thus when identifying familiar objects, the haptic processing system can achieve object constancy efficiently across hand changes and object-orientation changes, although this information is often stored even when it is task-irrelevant

Commentary: Neural correlates of expected risks and returns in risky choice across development

“Wisdom comes with age” is an oft-heard expression. It suggests that across development we improve in our ability to make decisions—but evidence for its validity is equivocal. In real-world decision-making, there is an adolescent-specific increased propensity to engage in behaviors associated with morbidity and mortality (e.g., road traffic accidents, unprotected sex, violence, drug, and alcohol abuse; Blum and Nelson-Mmari, 2004). However, this inverted u-shape developmental trajectory for risk-taking is typically not observed in laboratory-based studies (Defoe et al., 2015). As such, there exists a need to: (a) bridge the gap between laboratory and real world behavior; and (b) clarify the processes underlying developmental differences in decision-making to inform interventions that target a reduction in health-risking adolescent activities