Task 1. Arousal Theory and Practice

Stress

Biological aspects

Models on stress and performance

Yerkes-Dawson Law

Homeostatic system

Arousal theory

Easterbrook´s theory: Inverted U theory (focus on the first argument). Increases in arousal had the effect of progressively restricting the range of environmental events that could be processed. Low levels = reduces attention to not relevant environmental effects and that results in a better performance. In high levels, the effect is to cause neglect of task features, producing impairment in arousal (spotlight metaphor). Intermediate level of arousal = optimal. the inverted-U hypothesis considers an increase in selectivity [narrowing of attention

Non-linear relationship between stress and performance. Principles of the law: (1) performance is generally related to arousal in the form of an inverted U relation, being best at some intermediate level. (2)the optimum value of arousal is inversely relted to the difficulty of the task

Arousal: a general propertiy of the organism reflecting the overall level of activation of the system as a whole. Result of primarly of the degree of stimulation (internal or external)

Different from cumulative depeltion model: incorporate a principle of optimal stress. Based on the hypothesized inverted U relation between arousal and efficiency of performance

Dissociations

Cannon. Concepts of Homeostasis and "fight or flight" response

Selye: concept of stress: "the nonspecific response of the body to any demand upon it". 3 universal stages of coping with a stressor: (1) the general adaptation syndrome: intial alarme reaction, (2) a stage of adaptation associated with resistance to the stressor, (3) a stage of exhaustion and organismic death. ==> activation of the HPA axis

Modern concept of stress: Stress is a complex term referring to the psychological and physiological changes that occur in response to a real or perceived threat to homeostasis-. The response has a degree of specificity.

distress (conscious, perceived control of the situation) vs stress (unconscious)

Allostasis and allostatic load (sterling): Allostasis is achieving stability through change. Adaptation of setpoints, changing to a new set point in constrast to homeostasis (maintaining the same state). Allostatic load: effects of prolonged continous or intermittent activation of effectos involved in allostasis.// allostatic overload: long-term, wear and tear, cost of the adaptation.

Principles of operation of homeostatic system:

remember to look up the thermostat

heterostasis (selye): treatment induced, how the body respond to higher demands, establishment of a new steady state by changing the set-point.

Different stressors that influence arousal : anxiety (increase), drugs (increase), sleep deprivation, alcohol (decreases), noise, heat and time of day. Some of them will increase arousal, and other decrease it. The arousal will depend on how many stressors there are at the same time.

(1) negative feedback regulation:In response to a constant perturbing influence a system regulated by negative feedback yields a stable level of the monitored variable somewhere between the sensed and set values.

(2) Multiple effectors: three advantages of redundancy: 1) the multiplicity extends the range of external temperatures that can be tolerated to maintain constant the internal temperature, (2) when a single effector fails to function, others are activated to compensate, (3) one can pattern the use of the effectors as appropriate to maximize economy and efficiency

(3) Compensatory activation:having multiple effectors enables compensatory activation of alternative effectors,

(4) stressor-specifity: According to the allostatic concept of stress responses, acceptable activities of effector systems are coordinated in relatively specific patterns, including neuroendocrine patterns

(5) effector sharing: different homeostats can regulate the activity of the same effector system. -AHS (e.g. glucoprivation, emotional distress) & SNS (e.g. moderate exercise, cold)

(6) Sytems definition of stress: expectation do not match the current or anticipated perceptions of the internal or external environment, and this discrepancy elicits patterned, compensatory response.

GAD

Additive (separate effects of stressors could be additive) vs cumulative depletion*: when you get many stressors, your body can´t process all this stressors, and your performance is impaired. Combination of stressors that don´t allow to counteract the stressors

GAD- Generalized Adaptation Syndrome

Impairment can be the result of two little arousal, or two much, whereas incentive results in an optimal level for the task.
Evidence: (1) incentive counteracts the sleep loss, (2) noise also counteract the effect of the sleep loss, (3) incentive exacerbated the effect of noise

Difficulties with arousal theories: (1) sucess in accounting for the stress combinations, yet many inconsistencies remain, (2) impossible to falsify the theory due to ability to accomodate any pattern of results by the Inverted U, (3) the range of application of the theory is almost unlimited when task difficulty is taken into account/ can´t define effects of stressors independent of task performance, , (3) methology -not operational defintion of task difficulty- (4) phisiological basis of the arousal concept -different kind of arousal-

Graph: more stress, worst performance according to Selye (DATA B) for the Arousal theory, it is possible to see the different interactions (DATA A). According to gas, if we are sleep deprived and with a greater noise, you should have worst performance because of the depletion and cumulative effect. Arousal would predict the opposite.

Measurement of physiological responses

Startle response:protective reflex elicited by intense and unexpected sensory stimuli, mediated by subcortical neural circuitry including reticular formation modulated by limbic systems which is relevant for arousal. Often the eye-blink reflex is measure.In circumstances that generate fear, startle responses are potentiated (larger response with sudden noise). Positive emotion circumstances reduce startle responses to baseline.

Skin conductance response: index of electrodermal activity taken from electroces placed over hand surface of hand and feet. Measures emotions -fears and anxiety (higher arousal), sexual arousal. Limitations: other emotions can influence it.

Autonomous nervous system (ANS). regulates the functions of our internal organs (the viscera) such as the heart, stomach and intestines. The ANS is part of the peripheral nervous

HPA-axis Hypothalamus, pituitary gland and cortex of adrenal gland. Responsible for stress response, elicited by the encounter of an aversive stimulus, interpreted as potentially harmful for the individual.. The release of CRF (corticotrophin releasing factor) by the hypothalamus prompts the pituitary to disperse adrenocorticotropin-releasing hormone (ACTH) into the bloodstream. ACTH is detected by the adrenal cortex, facilitating the release of glucocorticoids such as cortisol. Negative feedback of cortisol on the hypothalamus and pituitary, suppressing the subsequent release of CRF and ACTH.. From class: cortisol increases metabolic glucose, activated the immune system and the body is more ready to respond

Sympathetic: fight or flight. Arouses body for action.Neurotransmitters: ganglionic neurons release noradrenaline, preganglionic acetylcholine and adrenaline  affects adrenergic receptors

Parasympathetic: rest and digest (calms the body -slowing heart beat and stimulating digestion after exertion (making effort) and doing quiet times. Nt. pre & post ganglionic acetylcholine (more inhibiting effects)  affects muscarinic receptors.

Enteric: the enteric nervous system is a meshwork of nerve fibers that innervate the viscera

The brain parts involved: ANS regulated by the hipothalamus, regulates autonomic nervous system functions include control of respiration, cardiac regulation, vasomotor activity and certain reflexes. Hipothalamus integrates autonomic functions, receives input from the limic system

AHS system: adrenomedullary hormonal system

3- Habituation (Goldstein)

4- Law of initial values (baseline

2- Acute stress  AHS and cortisol from the HPA axis -correlates more often together that wil SNS-

?

1- Sudden unexpected noise makes you curious, not necessary scared. Orientation reaction, one is courious for novelty. Unexpected noise not necessarily scary. Our sysem is oriented towards stimuli from environment. Hear rate decelerates because it is not immediately stressed. Startle response = valence of the stressor (is it positive or negative? scary or not?

  1. The measures don´t correlate because the systems are differently correlated, they are stressor-specific