Neural Basis of Attention

Neuropsychological Evidence Unilateral Neglect Syndrome

Drawings of a Visual Neglect Patient

Selective Visual Attention Posner and Raichle (1994) Brain Imaging Study.

Successful completion of the task requires the subject to execute 3 distinct actions: 1. Disengage from original point of focus. 2. Move to new stimulus. 3. Lock-in on new stimulus.

Posterior Parietal Lobe - Disengage Superior Colliculus - Move Pulvinar Nucleus - Lock-in

Attention Deficit Hyperactivity Disorder (ADHD)

Labels Minimal Brain Dysfunction Brain Injured Child Syndrome Hyperactive Child Syndrome Attention Deficit Disorder Attention Deficit Hyperactivity Disorder*

DSM IV – 3 Types of ADHD 1. Consistently Inattentive 2. Hyperactive and Impulsive 3. Combined

DSM IV – Diagnostic Criteria Behaviours must occur before age 7. Behaviours must continue for at least 6 months. Behaviours must be more frequent and severe than other children who are the same age. Behaviour must create a handicap in at least two areas of the person’s life.

ADHD Prevalence Identified in every country and culture studied, although prevalence rates vary substantially within and across countries. Between < 1% - 9% of all school-age children worldwide. ADHD males outnumber ADHD girls by 9 to 1.

ADHD Development Symptoms typically emerge between the ages of 3 and 5 years. Persist into adulthood for up to 2/3s of those diagnosed as children (Barkley, 1998)

ADHD Treatment Multimodal Treatment –Parent training in behaviour management strategies –Specialised education programs –Psychostimulants (e.g., Ritalin)

ADHD Causes

Environmental Risk Factors –premature birth –maternal tobacco use –maternal alcohol use –exposure to high levels of lead in childhood –brain injury

Genetic Factors Twin Studies –Heritability =.80 –Children who have an identical twin with ADHD are between 11 and 18 times more likely to be diagnosed with ADHD than children who have a non- twin sibling with ADHD. –Between 50 and 92% of individuals with ADHD twins will eventually be diagnosed with ADHD themselves.

Neural Basis of ADHD: Dopamine Hypothesis ADHD linked to: 1. Reduced sensitivity of dopamine receptors. 2. Overactivity of dopamine transporters.

ADHD Brain Imaging Study Lou, Hendrickson, and Bruhn (1984) Compared brain activity of ADHD and non-ADHD children. Found diminished CBF to frontal lobes in ADHD group. Ritalin increased CBF to frontal lobes and increased performance on behavioural measures of concentration.

Alcohol and Risk Taking: The Mediating Role of Attention

Why are people more likely to engage in risky behaviour when they are drunk? General Disinhibition Hypothesis Alcohol Myopia Hypothesis

General Disinhibition Hypothesis

Alcohol Myopia Hypothesis Steele and Josephs (1990) Alcohol consumption reduces cognitive capacity leading to a narrowing of attention to most salient cues in the environment.

Unprotected Sex Studies McDonald, Fong, Zanna, & Martineau, 2000

Laboratory Study Sample - young males, regular consumers of alcohol, not in a long-term romantic relationship, sexually, active, and regular condom users. IVs - (1) alcohol, placebo, no alcohol (2) impelling vs inhibiting cues present Task - View “Mike/Rebecca” video DV - Intention to engage in unprotected sex with Rebecca (9-point scale).

Impelling Cues Condition 1. Rebecca tells Mike she ________ on the pill. a. is b. is not Is it likely she will become pregnant? 2. At Rebecca’s apartment, she a. gives Mike the notes and encourages him to leave. b. offers Mike a drink and appears to want him to stay Do you think Rebecca is interested in Mike? –Followed by “sexual intentions” question.

Inhibiting Cues Condition 1. Rebecca tells Mike she _______ on the pill. a. is b. is not Can he be sure that she is telling the truth? 2. Who brings up the issue of condoms? a. Mike b. Rebecca Does it seem like Mike completely trusts Rebecca? Why would he be concerned about condoms? Followed by “sexual intentions” question.

Disinhibition Hypothesis

Alcohol Myopia Hypothesis Intoxicated

Actual Results Intoxicated

Field Study Sample – 452 patrons (167 females and 285 males) at 2 bars in Calgary Alberta. IVs - (1) Sober ( BAL.08) (2) Hand Stamps

Sex Vignette (female version) Imagine that you are single and that you run into a very attractive acquaintance while ordering a drink at the bar. The two of you begin to talk, and both of you find the conversation very enjoyable. He has a good sense of humour, and seems genuinely interested in what you are saying. It is clear there is definite chemistry between you and that you are interested in this person. You continue to spend time together throughout the night. When the bar closes, he offers to walk you home. We you get home he kisses you goodnight at the door. You decide to go inside and talk for a while. After talking, you and he begin to make out on the couch. Things progress and and you realize that you are both very interested in having sex with each other. You are on the pill, but neither of you have a condom. You discuss the possibility of going to a store, but there is not one nearby. You awkwardly discuss your sexual history, and he tells you that he does not sleep around.

Dependent Variable “If I were in this situation, I would have sex.” 1 = very unlikely, 9 = very likely

Results Males (4.68) reported stronger intentions to have sex than females (2.88). Interaction between intoxication level and gender. Interaction between between intoxication level and hand stamp type.

Gender x Intoxication

Hand Stamp x Intoxication

What are the main weaknesses of these studies?