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

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

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.

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.

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

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-

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?

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