Metcalfe, J. & Mischel, W. (1999). A Hot/Cool-System Analysis of Delay of Gratification: Dynamics of Willpower, Psychological Review, vol.106, no. 1

A hot, emotional "go" system is the basis of emotionality, fears as well as passions—impulsive and reflexive—initially controlled by innate releasing stimuli.

The hot emotional system is specialised for quick emotional processing and responding on the basis of unconditional or conditional trigger features.

The hot system is largely under "stimulus control," characterised by rapid automatic triggering, conditioned responding, inflexibility, stereotyping, and affective primacy.

Hot spots and cool nodes have different characteristics, different qualities, different connectivities to one another, lead to different responses, and are linked respectively to the hot system and the cool system gain-control mechanisms that filter or amplify the input activation on the specific nodes within their spheres of influence.

A subset of the internal hot nodes is contained within the hot system. Hot spots can be thought of as fragments of feeling. They may lead to “hot” responses. The responses determined by the hot spots are typically either approach or avoidance patterns.

Apart from the hot nodes, there is also a subset of cool nodes within the cool system. They are typically not immediate or direct approach-avoid patterns but rather verbal or nonverbal descriptions, statements, assertions, and commentaries—reflections rather than reflexes. 

• Developmental Factors
• Stress
• Chronic Environmental Factors
• Dispositional and Organic Factors
• Pharmacological Factors

The hot system develops early, whereas the cool system develops later. Thus, during the earliest years of life the hot system is functioning, whereas the cool system remains largely undeveloped. As the person ages, there is a shift of dominance from the hot to the cool system.

When the stress level increases, the cool system becomes increasingly dysfunctional, leaving the hot system to dominate processing. 

Environmental factors, such as chronic stress, has been shown to be correlated with volume decreases in the hippocampus (Sapolsky, 1996), a brain structure associated with episodic memory, which is a central function of thecool system. Chronic stress might result in a systematic shift from the hot-system to the cool-system.

Endogenous conditions, innate predispositions, physiological conditions, and diseases can impact selectively on the relative functioning of the cool or the hot system with predictable cognitive, emotional, and behavioral consequences.

Certain drugs may selectively augment or decrease hot/cool system functioning. For example, epinephrine or adrenaline appears to enhance hot-system processing. Propranolol, a drug sometimes used to alleviate hypertension, may have the opposite effect.

In this paper, the hot/cool analysis on delay of gratification is conducted with the example of the marshmallow test. It is an experimental design that measures a child’s ability to delay gratification. The child can choose to have one marshmallow immediately or two if he/she is willing to wait a bit. The minutes or seconds a child waits measures their ability to delay gratification.

Not exactly. According to the marshmallow experiment, exposure to the hot stimuli (marshmallow) made it virtually impossible for most of the children in the experiment to attain their chosen outcomes (wait for two marshmallows), defeating their efforts at willful control and leaving them disappointed.

Yes. By decreasing the activation of the Hot Spot Leading to impulsive action, it helps facilitate the ability to control oneself and persist to attain instant gratification. According to the marshmallow experiment, when the rewards (marshmallows) were out of sight, 75% of the children were able to wait the full time (15 min).

Yes. When avoiding attention to the rewards, it reduces the stimulation to the hot system and facilitates delay of gratification. According to the marshmallow experiment, those who attended to the rewards, thus activating the hot system more, tended to delay for a shorter time than those who focused their attention elsewhere, thus activating the cool system by distracting themselves from the hot spots. 

Maybe. If the distracting object were itself intriguing, it would have an even greater effect on diverting activation away from the relevant hot spot. Also, it is important to note that, the exposure to external stimuli should only activate non-relevant hot/ cool system networks. If the distractor activates the cool node that leads directly to the hot spot, the “go” response may be triggered, causing the person to pursue instant gratification. 

Yes. Self-generated cognitive distractions can serve to enhance control and attenuate the power of the hot stimulus as effectively as externally provided distraction. According to the marshmallow experiment, the children were asked to think about something fun, and the average waiting time was more than 12 minutes. 

It is worth noting that when exercising self-control with internal distractions, we tend to think about the reward more if we are told not to think about that reward specifically. The explicit mention of the not-to-be-thought-of object would prime the nodes for that object and thereby draw activation toward it, resulting in the increasing activation of that hot spots/ nodes, and leading to a "hot" response.

Yes. Take marshmallows as an example, a “cooler” version of it can be a photo of marshmallows. The photo contains the cool information about the object, such as its appearance, color, and shape, but it lacks the consummatory fragments that make it desirable and that elicit the “go” response. As one child put it, you can't eat the picture.

Yes. According to the marshmallow experiment, even when exposed to the real rewards, the children waited for them almost 18 min if they imagined them to be pictures rather than real. Likewise, delay was dramatically reduced when the children transformed the pictures into the real objects. It was their mental representation of the stimulus, either as real or as a picture, not its physical presence and reality, that controlled their behavior.

Yes. Delay of gratification tends to become less difficult and more likely with increasing age. When age increases, the cool system becomes more well-developed. The activated hot spot will automatically activate corresponding cool spots. This will prevent leading directly to a hot response. 

Yes, because the hot system is increasingly potentiated by stress, whereas the cool system is potentiated by low levels of stress and inhibited by high levels.