Introduction
Everyone is well aware of the dramatic impacts alcohol consumption can have on visual perception. Police demonstrations regarding drunk driving allow participants to wear “ drunk goggles” to experience the significant vision impairments associated with alcohol consumption. People usually envision the extremely drunk individual unable to stand upright, staggering out of a party, but the effects of alcohol consumption may be less obvious at times. Research shows that an individual’s state of intoxication can have an impact on the accuracy of their memory recall, especially after a weeklong delay (Compo et al., 2016). However, alcohol may have a significant impact on inattentional blindness as well as seen in a 2017 study by Harvey, Bayless, and Hyams. Inattentional blindness occurs when people fail to notice something in their field of vision because they are not paying attention to it. This can have devastating effects especially in the context of eyewitness testimony in which the eyewitness was incapacitated. Alcohol intoxication serves as a significant impairment to our memory recall for visual scenes largely due to inattentional blindness.
Literature Review
First of all, a 2016 study highlights the general memory impairments alcohol intoxication during encoding and retrieval can have on witnesses to a crime (Compo et al.). The researchers expressed that not much research has been conducted on this specific topic despite the prevalence of intoxicated witnesses at crime scenes. This study aimed to examine the effects of an individual’s state of intoxication at encoding versus recall to try and better understand when witnesses report more accurate or inaccurate details surrounding a crime (Compo et al., 2016).
The study examined approximately 249 undergraduate students that were compensated for their participation with research credit after being recruited from the university’s psychology recruitment website. Students were evaluated for their eligibility to participate and then assigned to either immediate recall or delayed recall. Each recall group assigned students to either sober, placebo, or intoxicated groups. The delayed recall group was divided even further by assigning students to either sober, placebo, or intoxicated recall groups as well. Thus, the study’s independent variable had twelve levels. Three of them in the immediate recall group and nine of them in the delayed recall group (Compo et al., 2016). Participants were placed in a setting that reflected that of a social drinking situation. After reaching the level of intoxication to which they were assigned, participants viewed a video of a mock crime. Participants were then interviewed immediately in they state in which they viewed the crime, or they were called in a week later and repeated the intoxication process before being interviewed.
Participants were tested on three measures: open-ended, cued recall, and confidence (Compo et al., 2016). Generally, the results found that there was no significant difference for the immediate recall groups in any state, but there were significant declines in accuracy when alcohol was involved in the delay groups. This study supports the notion that the primary impairment of alcohol on memory is the transfer of memories from short-term to long-term memory (Compo et al., 2016). This study is important when considering the general effects of alcohol on memory.
Another study looks more specifically at the effects of intoxication on peoples’ allocation of visual attention and whether or not intoxicated people would pay more attention to a noticeable event than a less noticeable event in their central field of vision and how many peripheral details intoxicated individuals would accurately recall (Harvey, Kneller, & Campbell, 2013). The researchers expressed that this study is important because it examines individual’s perception of an event by directly tracking their eye movements rather than having people participate only in recall exercises. This allows the researchers to examine exactly to what the participants were paying attention rather than what they could not remember (Harvey, Kneller, & Campbell, 2013).
This study does not state how participants were recruited, but the sample consisted of 106 undergraduate students that were offered either monetary compensation or course credit for their participation and assigned to either the alcohol or no alcohol groups (Harvey, Kneller, & Campbell, 2013). The researchers measured intoxication by measuring the students’ breath alcohol content. Students were then shown either an emotionally salient scene or a scene that had low emotional salience. Items in each scene were coded and either classified as central, peripheral, or contextual (Harvey, Kneller, & Campbell, 2013). Students’ eye movements were measured during their viewing of the stimulus scenes based on proportion and duration of attention allocated to the items in the scene. Students were also brought back the following day to perform a free-recall of the items in the scenes (Harvey, Kneller, & Campbell, 2013).
Results showed that the intoxicated participants paid more attention to the central items in the stimulus than the peripheral or contextual items and both groups paid more attention to the central items in the emotionally salient stimulus (Harvey, Kneller, & Campbell, 2013). The results supported the idea that alcohol intoxication is positively correlated with visual narrowing. However, this study did not examine or evaluate inattentional blindness specifically. The results showed a higher recall for peripheral items than central items; however, both visual stimuli groups contained more peripheral items than central items (Harvey, Kneller, & Campbell, 2013). Further research should be consulted to evaluate inattentional blindness specifically.
A 2006 study by Clifasefi, Takarangi, and Bergman looked more specifically at the effects of alcohol on inattentional blindness. This study is important because there has been a significant amount of research done on inattentional blindness and the effects of alcohol on visual attention but there have been few done on the effects of alcohol on inattentional blindness.
This study recruited forty-seven adults via a newspaper ad who were monetarily compensated for their participation in this experiment. The participants were randomly assigned to one of four groups. Participants were either told they got alcohol and did get alcohol, told they got alcohol but got a placebo, told they got a placebo but got alcohol, or told they got a placebo and got a placebo (Clifasefi, Takarangi, & Bergman, 2006). Participants entered a lab resembling a cocktail lounge and received their drinks based on the group to which they were assigned. The blood alcohol level of participants was measured, and after a brief delay, participants were shown the gorilla video and asked to pay attention to the white shirt team. Participants were then asked to rate their intoxication levels and any impairment they felt (Clifasefi, Takarangi, & Bergman, 2006).
Results showed that participants who received alcohol were less likely to notice the gorilla than participants who did not receive alcohol regardless of what they were told regarding their intoxication level by the researchers (Clifasefi, Takarangi, & Bergman, 2006). These results are consistent with the 2013 study by Harvey, Kneller, and Campbell. Alcohol intoxication did appear to narrow the participants’ allocation of attentional resources (Clifasefi, Takarangi, & Bergman, 2006). This study serves as a good basis for understanding the effects of alcohol on inattentional blindness.
A 2017 study by Harvey, Bayless, and Hyams took a different approach to evaluating the effects of alcohol inattentional blindness. This study evaluated the difficulty of the task in which participants were engaged and level of intoxication as potential impairments on the successful completion of the task and allocation of attentional resources (Harvey, Bayless, & Hyams, 2017). This study is important because it provides another angle at which to approach the impacts of alcohol on inattentional blindness and can provide support for previous studies.
The study used a convenience sample of 104 students at the university’s student bar. Students were approached at the bar after they had been drinking and asked to participate. Their intoxication levels were measured based on a self-report and a breath or blood alcohol content test (Harvey, Bayless, & Hyams, 2017). Participants were randomly assigned to complete the “ hard task” or the “ easy task.” The students viewed a modified version of the gorilla video. Participants in the “ hard task” group were asked to count aerial and bounce passes, and participants in the “ easy group” were asked to count passes generally. After viewing, participants were asked to record the number of passes they saw and anything unusual they noticed (Harvey, Bayless, & Hyams, 2017).
Results indicated that participants performed better on the easy task than the hard task as expected, and the participants that were less intoxicated performed better on the easy task than those that were more intoxicated. There was no significant difference in performance on the hard task. Despite this, the researchers still discovered a significant effect of alcohol on inattentional blindness for the easy task. A defense provided for the lack of significant difference on the hard task could be that the task was difficult enough that neither group was allocating significant attention to any item outside of the central focus (Harvey, Bayless, & Hyams, 2017).
Discussion
As evidenced by the reviewed articles, alcohol has negative impacts on our memory and increases our susceptibility to inattentional blindness. Beginning with memory, it is evident that witnesses to a crime that are intoxicated at the scene of the crime show much poorer recall of significant details than those that are sober witnesses to a crime. Not only do they recall fewer accurate details, but they also recall more inaccurate details (Compo et al., 2016). This could be significantly impacted by their poorer memory for visual scenes as supported by the 2013 study by Harvey, Kneller, and Campbell in addition to the increased susceptibility to inattentional blindness evidenced in the 2006 study by Clifasefi, Takarangi, and Bergman and the 2017 study by Harvey, Bayless, and Hyams.
Each of these studies provides a deeper look at the impacts of alcohol on our visual perception considering many different factors. Eventually, the studies became more and more specific with inattentional blindness appearing to be one of the most prevalent factors in this phenomenon due to the narrowing of our visual field. There is a plethora of research on inattentional blindness and the impacts of alcohol on our memory, but there is little research evaluating both. These articles build upon each other to provide a more detailed and specific explanation of why alcohol may impact recall of events experienced while intoxicated so significantly.
In terms of the implications this research provides for eyewitness testimony, jurors should take the testimony of witnesses that were drunk at the scene with a grain of salt. This especially true considering the study by Compo et al. showing that alcohol impacted participants’ recall even more significantly after a delay (2016). If witnesses to a crime are intoxicated, this study also suggests that they should be interviewed immediately for the most accurate testimony (Compo et al., 2016).
However, the studies also suggest that intoxicated individuals have poorer memory for visual scenes overall as their field of vision narrows (Harvey, Kneller, & Campbell, 2013) and they experience increased rates of inattentional blindness compared to their sober counterparts (Clifasefi, Takarangi, & Bergman, 2006). This in mind, jurors should be told when an eyewitness was intoxicated at the scene of a crime. It is evident that this has a significant impact on the witnesses’ memory and visual perception, and this should lead jurors to more carefully consider the information presented by such witnesses.
Finally, future research on the topic of alcohol and inattentional blindness should take an approach more geared towards eyewitness memory because alcohol is involved in so many crimes. Rather than exposing participants to the gorilla video used in the inattentional blindness studies by Clifasefi, Takarangi, and Bergman (2006) and Harvey, Bayless, and Hyams (2017), researchers could take an approach more geared towards witnesses to a crime by showing participants a video of a crime or setting up a mock crime. These studies provide a strong foundation for research on inattentional blindness and alcohol as it relates to eyewitness memory, and provides a clear direction for future research to strengthen our understanding of such an important topic.
References
- Clifasefi, S. L., Takarangi, M. K. T., & Bergman, J. S. (2006). Blind drunk: The effects of alcohol on inattentional blindness. Applied Cognitive Psychology , 20 , 697-704. https://doi. org/10. 1002/acp. 1222
- Compo, N. S., Carol, R. N., Evans, J. R., Pimentel, P., Holness, H., Nichols-Lopez, … & Furton, K. G. (2016). Witness memory and alcohol: The effects of state-dependent recall. Law and Human Behavior , 41 (2), 202-215. http://dx. doi. org/10. 1037/lhb0000224
- Harvey, A. J., Bayless, S. J., & Hyams, G. (2017). Alcohol increases Inattentional blindness when cognitive resources are not consumed by ongoing task demands. Psychopharmacology , 235 , 309-316. https://doi. org/10. 1007/s00213-017-4772-9
- Harvey, A. J., Kneller, W., & Campbell, A. C. (2013). The effects of alcohol intoxication on attention and memory for visual scenes. Memory , 21 (8), 969-980. http://dx. doi. org/10. 1080/09658211. 2013. 770033