Cary Stothart

The Pervasive Problem With Placebos in Psychology: Why Active Control Groups Are Not Sufficient to Rule Out Placebo Effects.

To draw causal conclusions about the efficacy of a psychological intervention, researchers must compare the treatment condition with a control group that accounts for improvements caused by factors other than the treatment. Using an active control helps to control for the possibility that improvement by the experimental group resulted from a placebo effect. Although active control groups are superior to “no-contact” controls, only when the active control group has the same expectation of improvement as the experimental group can we attribute differential improvements to the potency of the treatment. Despite the need to match expectations between treatment and control groups, almost no psychological interventions do so. This failure to control for expectations is not a minor omission—it is a fundamental design flaw that potentially undermines any causal inference. We illustrate these principles with a detailed example from the video-game-training literature showing how the use of an active control group does not eliminate expectation differences. The problem permeates other interventions as well, including those targeting mental health, cognition, and educational achievement. Fortunately, measuring expectations and adopting alternative experimental designs makes it possible to control for placebo effects, thereby increasing confidence in the causal efficacy of psychological interventions.

The attentional cost of receiving a cell phone notification.

It is well documented that interacting with a mobile phone is associated with poorer performance on concurrently performed tasks because limited attentional resources must be shared between tasks. However, mobile phones generate auditory or tactile notifications to alert users of incoming calls and messages. Although these notifications are generally short in duration, they can prompt task-irrelevant thoughts, or mind wandering, which has been shown to damage task performance. We found that cellular phone notifications alone significantly disrupted performance on an attention-demanding task, even when participants did not directly interact with a mobile device during the task. The magnitude of observed distraction effects was comparable in magnitude to those seen when users actively used a mobile phone, either for voice calls or text messaging.

Improving the safety of aging road users: a mini-review.

Older drivers are at greatest risk for injury or death as a result of a car crash. In this mini-review, we outline the normative age-related changes to perceptual, cognitive, and motor abilities that contribute to increased crash risk and decreased comfort with driving, and highlight specific driving scenarios and conditions that are particularly challenging for aging road users. Adopting a person-environment fit framework, we discuss how the roadway environment can be modified to better match the abilities of the aging driver. We also review evidence for the efficacy of training interventions that aim to change the abilities and strategies of the aging driver to better match the demands of the driving environment. Evidence suggests that specific changes to the roadway and driver training strategies can bring the abilities of the older driver back into alignment with the demands of the driving task. A focus on both approaches will help ensure the safety of all road users as the number of aging drivers greatly increases over the next few decades.

Is the Effect of Aerobic Exercise on Cognition a Placebo Effect

A number of studies and meta-analyses conclude that aerobic fitness (walking) interventions improve cognition. Such interventions typically compare improvements from these interventions to an active control group in which participants engage in non-aerobic activities (typically stretching and toning) for an equivalent amount of time. However, in the absence of a double-blind design, the presence of an active control group does not necessarily control for placebo effects; participants might expect different amounts of improvement for the treatment and control interventions [1]. We conducted a large survey to explore whether people expect greater cognitive benefits from an aerobic exercise intervention compared to a control intervention. If participants expect greater improvement following aerobic exercise, then the benefits of such interventions might be due in part to a placebo effect. In general, expectations did not differ between aerobic and non-aerobic interventions. If anything, some of the results suggest the opposite (e.g., respondents expected the control, non-aerobic intervention to yield bigger memory gains). These results provide the first evidence that cognitive improvements following aerobic fitness training are not due to differential expectations.

The costs (or benefits) associated with attended objects do little to influence inattentional blindness

We sometimes fail to notice unexpected objects or events when our attention is directed elsewhere, a phenomenon called inattentional blindness. We explored whether unexpected objects that shared the color of consequential objects would be noticed more often. In three pre-registered experiments, participants played a custom video game in which they avoided both low- and high-cost missiles (Experiment 1 and 2) or tried to hit rewarding missiles while avoiding costly ones (Experiment 3). After participants had played the game for about 8min, an unexpected object moved across the screen. Although participants selectively avoided more costly missiles when playing, they were no more likely to notice an unexpected object when its color was associated with greater costs. Apparently, people are no more likely to notice unexpected objects that are associated with negative consequences. Future research should examine whether objects that are themselves consequential are noticed more frequently.

Exploring the Effects of Video Game Experience and Motivation on Visual Processing

Boot W.R., Blakely D.P. & Simons D.J. (2011). Do action video games improve perception and cognition? Frontiers in Psychology, 2:226. doi: 10.3389/fpsyg.2011.00226 Green, C. S. & Bavelier, D. (2003). Action video game modifies visual selective attention. Nature, 423, 534-537. Green, C.S. & Bavelier, D. (2006). Effect of action video games on the spatial distribution of visuospatial attention. Journal of Experimental Psychology: Human Perception and Performance, 32, 1465-1468. Note: Error bars represent +/1 standard error of the mean.

Clarifying the role of target similarity, task relevance and feature-based suppression during sustained inattentional blindness

How is feature-based attention distributed when engaged in a challenging attentional task? Thanks to formative electrophysiological and psychophysical work, we know a great deal about the spatial distribution of attention, but much less is known about how feature-based attention is allocated. In a large-scale online study, we investigated the distribution of attention to color space using a sustained inattentional blindness task. In order to query what parts of color space were being attended or inhibited, we varied the color of an unexpected stimulus on the final trial. Noticing rates for this stimulus indicate that when engaged in a difficult task that involves tracking items of one color and ignoring items of two different colors, observers attend the target color and inhibit the to-be ignored colors. Further, similarity to the target drives detection such that colors more similar to the target are more likely to be detected. Finally, our data suggest that when possible, observers inhibit regions of color space rather than individuating specific colors and adjusting the level of inhibition for a particular color accordingly. Together, our data support the notion of feature-based suppression for task relevant (to-be ignored) information, but we found no evidence of an inhibitory surround based on target color similarity.

Age Effects on Inattentional Blindness: Implications for Driving

We may fail to notice things in our environment because our attention is directed somewhere else, a phenomenon called inattentional blindness. Our susceptibility to inattentional blindness increases as we age. We explored three potential moderators of the age and inattentional blindness relationship: (1) the spatial proximity of the unexpected object to our focus of attention; (2) the match between the features of the unexpected object and those we have prioritized—our attention set; and (3) the salience of the unexpected object. Using a large sample of participants, we found no evidence that any of these moderate the effect that age has on inattentional blindness; the effect of age is robust. We discuss the implications for older drivers.

Action Video Game Experience Does Not Predict Multiple Object Tracking Performance

Tasks: Multiple object tracking task, questions about video game experience Sample: Amazon Mechanical Turk Coding: JavaScript, PHP, HTML/CSS Overt Recruiting: Study description explicitly mentioned action gaming experience (75 gamers, 84 non-gamers) Covert Recruiting: No mention of gaming experience until after the study (72 gamers, 108 nongamers) The relationship between action video game experience and object tracking performance is not robust. Pre-registered: http://goo.gl/s6gLX7 Large sample Direct comparison of overt and covert recruiting This Study Multiple Object Tracking Task

Author accepted manuscript: Semantic associations do not modulate the visual awareness of objects

When observers adopt a category-level attentional set, objects that belong to the same category as this attentional set are more likely to enter awareness. For example, a driver who is monitoring the road for cars may be more likely to notice an oncoming car than a pedestrian who is crossing the road. Semantic associations between categories are also known to influence the deployment of attention, but it is unclear whether these associative relationships can influence the visual awareness of objects. To address this issue, we conducted four experiments using an inattentional blindness task. Participants tracked moving images of animals (e.g., monkeys or rabbits). On the last trial, an unexpected object that could belong to the same category as the tracked objects (i.e., a monkey or rabbit) or a semantically associated category (i.e., a banana or carrot) moved across the display. Participants were more likely to notice this object when it was visually salient or belonged to the same category as the tracked objects. However, they were no more likely to notice objects that shared a semantic association with the tracked objects. Thus, although categorical relationships play an important role in the visual awareness of objects, this effect does not extend to associative relationships among objects.