Question

Which of the following are examples of positive feedback, and which are examples of negative feedback? a) a warming arctic melts ice, making it darker, absorbing more solar energy b) if the earth's temperature rises, its infrared radiation to space increases, providing additional cooling c) a car sits in a dip; pushing it forward results in a backward force, while pushing it backward results in a forward force d) a car sits on a hill; pushing it either way results in an acceleration (more force, thanks to gravity) in that direction e) a child wails loudly and throws a tantrum; to calm the child, parents give it some candy: will this encourage or discourage similar behaviors going forward?

Short answer

a) Warming Arctic b) Earth's temperature rise c) Car in a dip d) Car on a hill e) Child's tantrum Answer: Positive feedback examples: a) Warming Arctic, d) Car on a hill, and e) Child's tantrum. Negative feedback examples: b) Earth's temperature rise, and c) Car in a dip.

Step-by-step solution

Example a) Warming Arctic

This example is an example of positive feedback. As the ice melts, the darker surface absorbs more solar energy, which further accelerates the melting process. The original condition (warming arctic) is amplified, leading to even more ice melting.

Example b) Earth's temperature rises

This example is an example of negative feedback. When the Earth's temperature rises, it releases more infrared radiation into space, which helps cool the Earth down. The original condition (increased temperature) is counteracted, resulting in a stabilizing effect.

Example c) Car in a dip

This example is an example of negative feedback. When the car is pushed forward, a backward force is generated, and when pushed backward, a forward force is generated. In both cases, the forces are acting to counteract the original action, resulting in a stabilizing effect.

Example d) Car on a hill

This example is an example of positive feedback. When the car is pushed in either direction on the hill, gravity adds more force, causing the car to accelerate in the direction it is being pushed. The initial condition (pushing the car) is amplified, leading to an increase in the car's speed.

Example e) Child's tantrum

This example can be interpreted as an example of positive feedback. When the child throws a tantrum, the parents give candy to calm the child. This action reinforces the child's behavior, making it more likely that they will exhibit the behavior again in the future. The reward (candy) amplifies the initial condition (tantrum), encouraging similar behaviors going forward.

Key concepts

Positive Feedback

Positive feedback is like a snowball rolling down a hill, getting bigger and faster with each roll. It's a process that amplifies or speeds up changes, leading to exponential growth or cascading effects in many systems. This is because the output of a system enhances the original input. Let’s take a closer look:

• Example of Positive Feedback in Nature: The warming Arctic is a classic example. As the Earth's climate heats up, polar ice melts. This reveals darker water or land underneath, which absorbs more sunlight compared to the reflective ice. This additional heat causes more ice to melt, further warming the area. It's a cycle of amplification.

Such feedback loops can often lead to runaway effects, which are sometimes difficult to control. They drive changes away from equilibrium, making them critical to understand in fields like ecology, climatology, and even economics.

Negative Feedback

Negative feedback is a stabilizing mechanism that works to counteract changes in a system, aiming to maintain equilibrium. Imagine using your hands to steadily balance a seesaw. The idea is simple: when things start to tip one way, the system makes adjustments to bring everything back in balance. This type of feedback is essential for maintaining stability in various systems.

• Example of Negative Feedback in Earth’s Climate: Consider how the Earth regulates its temperature. When Earth's temperature rises, it emits more infrared radiation to space, which helps to cool the planet down. This response opposes the initial warming, serving to stabilize the climate by ensuring it doesn't spiral out of control.
• Mechanical Illustration: The car sitting in a dip also demonstrates negative feedback. Push it one way, and the forces at play push it back towards the center, maintaining its stable position.

Negative feedback is prevalent in many regulatory systems, from biological processes in living organisms to technological systems like thermostats.

Stabilizing Effect

The stabilizing effect is often the result of negative feedback processes working to maintain balance in a system. It's like a tightrope walker using a pole to stay balanced. The aim is to resist changes that could destabilize or disrupt the system. This effect is crucial for systems to operate efficiently and stay within safe operational limits.

• Biological Systems: In your body, numerous stabilizing effects are constantly at work. For instance, your body's ability to maintain a stable internal temperature, despite fluctuations in external temperatures, is thanks to negative feedback loops like sweating or shivering.
• Physical Systems: In our earlier mechanical example, a car in a dip represents a stabilizing effect. Forces work against the direction it is pushed, helping to keep it stable and preventing it from rolling away unexpectedly.

Stabilizing effects are vital to the resilience of systems, allowing them to resist shocks and maintain function over time.

Amplifying Effect

An amplifying effect, driven by positive feedback, is a process that strengthens or increases the initial input, similar to turning up the volume on a speaker. This effect can drive significant changes in systems, often leading to more pronounced outcomes.

• Illustrative Scenario: Consider a car on a hill. When you push it either way, gravity provides extra force to accelerate it downhill. This causes the car to move more swiftly in the direction of the push, an example of an amplifying effect.
• Social Behavior: In behavioral contexts, such as a child's tantrum, giving candy can reinforce the behavior. The initial whining is amplified or increased, making it more likely to occur in the future.

Amplifying effects can lead systems to extreme states or enhanced performances, which can be either beneficial or detrimental, depending on the context. Understanding these effects is vital for forecasting system behavior in science and policy frameworks.