Alcohol’s effect on Inhibitory Mechanisms of Visual Attention

1. Alcohol’s effect on Inhibitory Mechanisms of Visual Attention by Ben Abroms

2. My Background • Born: Toronto, Canada • Dual Citizenship • Undergrad: University of Western Ontario • Began focus on cognitive processes • Grad School: University of Kentucky • Master’s in Animal Cognition • Ph.D. in Cognitive Neuroscience

3. Overview • Acute Alcohol Intoxication • Drunk Driving • Why study acute alcohol effects on attention? • Attention • Attention and inhibition • 2 Cognitive Tasks • IOR model • Delayed Ocular Response Task

4. What we know about drugs. Mmm-Kay

5. Acute Alcohol Intoxication • Drunk Driving – $9 billion a year (NCPA, 2001). • Majority of those with DUI in past 12 months not dependant or abusers (Caetano & McGrath, 2005). Over 500 000 people injured per year!

6. Acute Alcohol Intoxication Fatal Crashes: BACIncrease 0.05-0.09 11X 0.1-0.14 48X >0.15 380X (Zador, 1991)

7. Acute Alcohol Intoxication • Drunk Driving (continued) (National Highway Traffic and Safety Admin., 2004)

8. Acute Alcohol Intoxication • Why does increasing BAC result in increased accident risk? • Cognition & Behavior

9. Acute Alcohol Intoxication • We also know that……. • Alcohol increases risky behavior (Piombo & Piles, 1996). • Alcohol Myopia (Steele & Josephs, 1990). • Disinhibition (Fillmore, 2003). • The more complex the more impaired by alcohol (Maylor, Rabbitt, & James 1992). • Alcohol slows information processing(Halloway, 1995).

10. Alcohol and Information Processing • Information processing comprised of three stages (eg. Welford, 1952). • Stimulus Identification • Response Selection • Response Execution • Attention is more than just a spotlight! Attention

11. Attention • Attention is an important component of information processing. • Attention directs cognitive resources to relevant stimuli and away from irrelevant stimuli (Pashler, 1998). • Impairment of attention = reduction in the capacity of information processing.

12. Attention • Vague Concept • Internal vs. External • Controlled vs. Automatic • Relation to Working Memory

13. Attention and Inhibition • Attention depends on inhibitory influences. • Protection from interference • Attention allocation (Bjorklund & Harnishfeger, 1995) • An Example: Negative Priming

14. Attention and Inhibition • Negative Priming Green Red Black Orange Blue Green Negative Priming Positive Priming

15. Attention and Inhibition (and alcohol) • Alcohol selectively impairs negative priming BUT has no effect on positive priming (Fillmore, Dixon & Schweizer, 2000a, 2000b). • Alcohol impairs the inhibitory gating processes that serve as mechanisms of selective attention. • Under the drug selective attention more susceptible to interference from irrelevant sources.

16. Present Research • Two tasks • Both measure an inhibitory mechanism of visual attention. • Reductionistic Approach • Need to understand how drugs impair the components of cognition that higher processes (i.e., WM, attention) depend on. • Driving is a very complex behavior. • Medication development.

17. Alcohol and Inhibition of Return Posner & Cohen, 1984

18. Inhibition of Return • Makes visual search more efficient(Klein & MacInnes, 1999). • Automatic. • Present at birth(Clohessy, et al., 1991). • Maximal IOR at 350 – 650 ms(Klein, 2000). • Lasts upwards of 2.5 seconds(Samuel & Kat, 2003). • Flexible: location vs. object based(Jordan & Tipper, 1998). • Involvement of the frontal eye fields(Ro, Farne, & Chang, 2003). • Functions in all modalities(Spence, Nichols, & Gillespie, 1998). • Sensitive to inhibitory deficits in ADHD and schizophrenia(Li, Chang, & Lin, 2003; Larrison, Briand, & Sereno, 2002).

19. Methods • Subjects: 10 healthy undergraduates. • Drinking habits: no gender effects, report drinking 4-5 standard drinks per occasion and 1.5 – 2.5 times a week. • Procedure: • Phone Screen • Answer questionnaires • Familiarization • More questionnaires • Practice task • 2 alcohol test sessions, 0.65 g/kg and 0.0 g/kg (placebo). • Drink • Perform test

20. Methods • (2) Test Sessions • Provide urine sample • Pre-session checks • Receive beverage (0.0 or 0.65 g/kg of pure alc) • Wait 30 min. • Perform Task • Wait for BAC to fall (< 0.04) • Paid and released back into the wild

21. IOR Layout 500 ms +

22. IOR Layout 500 ms +

23. IOR Layout 20 ms +

24. IOR layout 10 ms +

25. IOR layout 20 ms +

26. IOR layout Target presented 450, 900 or 1200 ms later and lasts 1000 ms. +

27. Alcohol and IOR • Hypothesis: Based on previous studies showing alcohol selectively impairs inhibitory mechanisms of attention, we predicted the drug would also disrupt proper IOR functioning. • In other words…under alcohol we expect to see the RT required to detect the target decrease when cues and targets presented in same location.

28. IOR Task Breakdown • During a Test…. • 300 trials. • 20% are catch trials (reduce anticipatory responding). • The remaining 240 trials are split between control and IOR trials. • Each SOA presented equal number of times. • Target appears an equal number of times at right and left locations.

29. Alcohol and IOR: Results Taken from Abroms and Fillmore, 2004

30. Alcohol and IOR: Results • Alcohol reduced the duration of IOR. • Reduced duration means attention allowed to return to previously scanned area earlier, increasing redundant information extraction. • Suggests the drug reduces the efficiency with which information is extracted from the visual environment.

31. IOR and Stimulant Abuse

32. Conclusions • Evidence is accumulating that shows alcohol disrupts the normal functioning of inhibitory mechanisms important for efficient attention allocation. • However, a more accurate assessment of drug effects on visual attention could be gained by looking directly at eye movements.

33. Attention and Eye Movements • Why use eye movements as an index of attention shifts? • Both serve same function. • Better understanding of the circuitry involved. • Attention shift precedes eye movement. • Are dissociable but rare. (Hyona, Radach & Deubel, 2003) Conclusion: Eye movements provide a more valid assessment than manual responses.

34. Current Eye Movement/Alcohol Research • Very little has been done. • Reliably found that alcohol slows saccade initiation and speed (i.e., Blekher et al., 2002; Vassallo & Abel, 2002). • Effects on saccade accuracy equivocal. • Investigations of alcohols effect on the ability to inhibit eye movements use the anti saccade task.

35. Anti Saccade Task • Participants instructed to make a speeded saccade in direction opposite but equal target (Hallet, 1978). +

36. Anti Saccade Task and Alcohol • Reliably found that alcohol improves anti saccade performance. • Under alcohol fewer incorrect pro saccades are made (e.g., Kahn et al. 2003). • Also, reliably found alcohol slows the speed of the saccade.

37. WHAT!?! • Anti saccade results are at odds with both the behavioral literature and studies using other tasks that measure inhibitory attentional mechanisms. • Could anti saccade results be due to a speed vs accuracy trade-off?

38. New Task • Needed: • A task with simpler response because alcohol’s effect on RT shown to be proportional to task complexity (Maylor et al., 1992). • A task that actually requires the complete suppression of all eye movements as it has been shown the availability of an alternate response ameliorates alcohol’s effect on behavioral control (Abroms, Fillmore & Marczinski, 2003).

39. The Delayed Ocular Return Task (DORT) Ross et al., 2000 • Requires a simple saccade be made to target location. • Must inhibit reflexive saccade. • Saccade must be inhibited until go signal is given. • Also provides RT and visuospatial WM measures. • DORT is sensitive to inhibitory deficit in ADHD and Schizophrenia (Ross et al., 2000). • Controlled process.

40. DORT Layout 1500 ms +

41. DORT Layout 100 ms +

42. DORT Layout 800, 1000 or 1200 ms +

43. DORT Layout 1000 ms

44. DORT Layout Next fixation appears at correct saccade location. +

45. Methods • Criterion Measures • Saccades classified as primary or secondary. • Primary saccades classified as premature, valid or late. • Valid primary saccades measured for accuracy and speed.

46. DORT Hypothesis • We predicted that alcohol would decrease control over eye movements. Specifically we expected an increase in the number of premature saccades. • We hoped there would be no effect on RT. • No predictions were made concerning saccade accuracy.

47. Methods • Apparatus: • DORT performed on a PC computer. • 5 target locations, separated by 5.62 degrees. • Test of 96 trials presented in 2 blocks of 48. • Presented each angle, in each direction an equal number of times. • 1 minute break between blocks. • 7 minutes total run time.

48. Methods • Apparatus (continued): • Eye tracker is accurate to 0.5 of a degree of visual angle and has a resolution of 0.5 of a degree. • Locations were sampled at 60 Hz and given an X/Y coordinate. • Coordinates were used to define fixations and saccades. • To start a fixation the program looked for a period of at least 100 ms in which the line of gaze had a standard deviation of less than 0.5 degrees of visual angle. • To end the fixation the program looked for a period of at least 50 ms in which the gaze position was at least 1 degree of visual angle away from the initial fixation position. • The final fixation position was the average of all data sampled between the beginning and end of the fixation. • Both saccade duration and visual angle moved were calculated using fixation locations and durations.

49. Results

50. Results • No effect of alcohol on number of valid or late saccades. • No effect of alcohol on accuracy or RT of saccades. • 377.6 ms under placebo and 377.7 under alcohol. • Interestingly, those with worse accuracy scores were disrupted to a greater degree by alcohol.