neurocognitive processes

neurocognitive processes

The field of neurocognitive processes is one that elicits a lot of interest among researchers in an attempt to understand everyday conditions associated with the reward system influence. In particular, the difference between Value-driven attentional capture (VDAC) and saliency or contingency were of specific interest to the researchers Watson, Pearson, Chow, Theeuwes, Wiers, Most and Le Pelley (2019) in their paper “Capture and Control: Working Memory Modulates Attentional Capture by Reward-Related Stimuli”.  Working with the hypotheses that minimum interference by goal-irrelevant distractors can be achieved through selective visual attention provided by goal-directed working memory, the researchers did experiments on whether resource-dependent control processes could impact the effect of the presence of a reward on the attentional capture as much as they did on physical salience. Their question was whether the influence of reward on attention capture is entirely automatic or the cognitive control processes can help reduce the influence when the capture is not as per one’s current goals. With recent studies having demonstrated the association between reward and stimuli in attention capture, the study question is of importance as it helps provide more information on the behavior of attentional bias in the case of a drug related stimuli for an addict.

For this research, the Watson, Pearson, Chow et al. performed two experiments. In the first experiment, the oculomotor capture, measured through the saccade made using a Tobii TX300 eye tracker was the dependent variable and the singleton distractors acted as the independent variables. This research involved 30 participants (18 females; mean age 21.3 years and SEM =0.5) who were given a course credit payment of AUD 25 and a bonus dependent on their performance (the reward). The test was individually done with the eye tracker positioned on a 23-inch monitor and the participant’s head positioned 60 cm away from the screen in a chin rest position.

Each individual was to stare at a fixated central cross and after 300ms the cross and circle turn yellow to indicate that the visual search task was about to begin. The search involved six shapes- a diamond and five circles placed evenly around an imaginary ring at an angle of 10.1 degrees. In some trial, one of the circles was colored blue or orange and the rest of the circles were grey. The colored ones were the singleton distractors and for half the group, blue represented the high reward color and the other half, orange was the high reward color. The participants were expected to dart their eyes as quickly as possible to the diamond and a response was registered when 100ms of gaze time was directed towards the target center. If the trial had a high reward singleton and rapid response was registered, the participant earned 500 points but if it was a low reward singleton or none, a rapid response earned him/her 10 points. A gaze towards the distractor though would be recorded as an omission trial hence no reward. A total of 36 trials was done, 15 with high reward distractor, 15 low, and 6 had no distractor.

For the memory task, in the high load tests, the trial begun by the participants being shown the digits 1 to 5 randomly arranged for about 1000 ms followed by a 500 ms blank interval then the search task as described above was performed. Immediately after giving the search task feedback, they were supposed to enter the digit that previously appeared in one of the randomly chosen memory set locations. A delay of 5s resulted in an error tune, also if the entry done was wrong. In a low load test, a similar test was done but only one digit was shown out of the five at the beginning of the trial.

Before beginning the trials, the participants were explained to how the study would be done and they were given a demonstration chance to ensure they had understood. Also, the information on conversion rates for their rewards was not given forth and they were only informed that they would be given a bonus of between AUD 8 AND 13 depending on their performance. The first three tasks done were only visual search before the memory load was introduced after which the high and low load memory tasks were alternated with short breaks in between the trials.

After data analysis, the results on the memory task accuracy yielded were generally high though significantly higher in the low-memory condition. This led to the conclusion that the memory task conditions placed different loads on the cognitive resources. As for the visual search task, omission trials were found to be more likely when a high reward distractor was shown compared to when a low reward distractor appeared. This demonstrated the effect of reward on attention capture. Also, the memory load had an effect where participants were most likely to fixate on the distractors regardless of high or low value in the presence of a high memory load compared to when on a low memory load task. The interaction between the high memory load and low memory load was significant though, with the VMAC effect being greater in the high load compared to low load memory task. The influence of the reward on the attention capture was thus demonstrated to the enhanced when one had a high memory load. The visual search omission trials also revealed the effect of physical saliency on the proportion of omissions, with the omissions being more likely in the presence of a colored singleton than in its absence. Generally, it was shown that under a high memory load, the influence of physical saliency on attention capture was enhanced.

In the second experiment, the replicability of the results obtained in the first experiment was assessed in a more sensitive test of the effects of the memory load on the capture by reward related stimuli. The test involved the use of an occasional distractor containing both high and low reward distractors together in the search array so that they would both compete for attention from the participant. The researchers expected more eye movements to distractors when the participants were under high memory load as per the results on the first experiment and since both distractors had equal physical salience, a higher memory load was anticipated to cause a distractor related eye movement towards the high reward distractor if at all memory load increased distraction by reward.

43 participants, each being paid a credit course of 30 AUD and a performance based bonus were recruited for the study. One participant was however excluded for having excess time outs. Orange was the high reward distractor color for half the study population and blue, for the other. The design of the study was largely similar to that in experiment one where the participants first completed 3 search tasks alone before memory load tasks were added in the following ten blocks. The trial featured 44 trials, 15 with single high reward destructor, 15 of low, 6 with no destructor and 8 with both high and low distractors. For the single distractors, the singleton distractor was randomly placed one or two locations away from the target, similar to the non-salient gray circle chosen to act as the omission causing stimulus. In the trial with both high and low reward distractors, each was placed as described above with the other placed same way but on the opposite side of the target. The reward points for the both distractor trials was 500 points which were subject to omission when the gaze was detected on either of the distractors. The memory load was increased to six instead of five digits as in the first experiment.

The proportion of omission trials was still the dependent variable. The result of the memory task accuracy revealed that accuracy was significantly higher in the low-memory condition compared to the high memory condition. The VMAC effect was demonstrated by having more reward omissions oh high single distractor type than low single distractor type, and as in the first experiment, the VMAC effect was magnified under high memory load. By analyzing the results from both high and low distractor type study, the above observation was supported. Competition between high and low value distractors also yielded the under a high memory load, the distractor related eye movement was directed to the high reward distractor.

As this study tried to investigate if cognitive control can be used in preventing oculomotor capture by salient distractors, it was noted that sometimes the attention could be captured by physically salient distractors and this capture was also influenced by presence of a reward. Supporting previous work they had done, Watson, Pearson, Chow et al. the results of this experiment showed that one was more likely to be destructed in the presence of a high reward destructor and hence look at it even when it meant a higher loss of the rewards promised. Moreover, both physical saliency and reward effects on oculomotor capture are magnified in conditions of high memory load. The second experiment served to show the counterproductive effect of reward on VMAC in the presence of a high memory load where participants had a selective increase in oculomotor capture of high reward distractors under such condition.

The findings of this research answered the questions raised before, that the prioritization of distractors that are reward related is not purely an automatic process but that it can be controlled and be reduced in the presence of sufficient cognitive resources. This hence supports the hypothesis that working memory can provide selective visual attention to allow for minimal interference by goal irrelevant distractors in a goal oriented task.

In conclusion, the implications of this research are important, especially in the clinical context where they can be used to explain the reward-related intentional biases leading to compulsive behaviors as observed in cases like addictions. While previous studies had shown the relationship between the bias and substance abuse to be moderated by differences in executive control in different individuals, this study showed the direct role of executive control in the relationship. Individuals (addicts) trying to abstain from drug and substance abuse were more likely to engage in drug behavior nonetheless in the presence of a visual drug stimuli if they had low cognitive resources.