The study of animal behavior, or ethology, often involves observing animals in their natural habitats to understand the evolutionary significance of their actions. One key concept is the 'fixed action pattern,' a sequence of unlearned acts directly linked to a simple stimulus. Once initiated, the fixed action pattern is usually carried to completion. For example, a male stickleback fish, which normally attacks other males that invade its territory, will also aggressively attack inanimate red-bellied models, while ignoring realistic fish models that lack the red underside. The red belly acts as the sign stimulus that triggers the aggressive fixed action pattern.
Consider what the red belly does in the stickleback fish example.
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What is the primary function of the 'sign stimulus' as described in the passage?
The study of animal behavior, or ethology, often involves observing animals in their natural habitats to understand the evolutionary significance of their actions. One key concept is the 'fixed action pattern,' a sequence of unlearned acts directly linked to a simple stimulus. Once initiated, the fixed action pattern is usually carried to completion. For example, a male stickleback fish, which normally attacks other males that invade its territory, will also aggressively attack inanimate red-bellied models, while ignoring realistic fish models that lack the red underside. The red belly acts as the sign stimulus that triggers the aggressive fixed action pattern.
Look for the description of what happens once a fixed action pattern starts.
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The passage suggests that a fixed action pattern is typically:
Artificial neural networks (ANNs) are computing systems vaguely inspired by the biological neural networks that constitute animal brains. An ANN is based on a collection of connected units or nodes called artificial neurons, which loosely model the neurons in a biological brain. Each connection, like the synapses in a biological brain, can transmit a signal from one artificial neuron to another. An artificial neuron that receives a signal can process it and then signal additional artificial neurons connected to it. In common ANN implementations, the signal at a connection between artificial neurons is a real number, and the output of each artificial neuron is computed by some non-linear function of the sum of its inputs. These systems 'learn' to perform tasks by considering examples, generally without being programmed with any task-specific rules.
Find the comparison made for the connections in an ANN.
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The passage states that the connection between artificial neurons in an ANN is analogous to what in a biological brain?
Artificial neural networks (ANNs) are computing systems vaguely inspired by the biological neural networks that constitute animal brains. An ANN is based on a collection of connected units or nodes called artificial neurons, which loosely model the neurons in a biological brain. Each connection, like the synapses in a biological brain, can transmit a signal from one artificial neuron to another. An artificial neuron that receives a signal can process it and then signal additional artificial neurons connected to it. In common ANN implementations, the signal at a connection between artificial neurons is a real number, and the output of each artificial neuron is computed by some non-linear function of the sum of its inputs. These systems 'learn' to perform tasks by considering examples, generally without being programmed with any task-specific rules.
The last sentence describes the learning process of ANNs.
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According to the passage, how do ANNs typically learn to perform tasks?
The concept of 'placebo effect' refers to a beneficial health outcome resulting from a person's anticipation that an intervention—pills, procedures, or other treatments—will help them. For a treatment to be considered a placebo, it must not have a direct physiological effect on the condition it is purported to treat. The strength of the placebo effect can vary significantly depending on factors such as the patient's mindset, the perceived credibility of the treatment or practitioner, and even the color or cost of a placebo pill. While ethically complex, understanding the mechanisms behind the placebo effect is crucial for designing effective clinical trials and for harnessing its potential in patient care.
What role does 'perceived credibility' play in the placebo effect?
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The passage suggests that the perceived credibility of a treatment can:
GRE Reading Comprehension Practice Quiz 3
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