classic picture of positive feedback among ...

Simin93

Senior Member
Persian-Iran
Hello friends
The underlined part doesn't make sense to me, could you please help me? I know the meaning of each word, but I can't understand this part generally

The picture of Teotihuacán (the name of a city) that emerges is a classic picture of positive feedback among obsidian mining and working, trade, population growth, irrigation, and religious tourism. The thriving obsidian operation, for example, would necessitate more miners, additional manufacturers of obsidian tools, and additional traders to carry the goods to new markets.

Reference: TOEFL Sample

Thank you in advance.
 
  • Egmont

    Senior Member
    English - U.S.
    Positive feedback means that an increase in A leads to an increase in B, which then leads to a further increase in A. This can be good or bad, depending on the situation.

    A common example is feedback in an audio system when there is a microphone near a speaker. A small increase in output from the speakers (A) leads to an increase in input to the microphone (B), which in turn leads to a further increase in output from the speakers. This process only ends when it reaches the limit of the amplifier or the speaker. (Most people find this feedback annoying and try to stop it quickly.)
     

    Andygc

    Senior Member
    British English
    You have underlined two items in the list - "trade" is a separate item
    positive feedback among
    - obsidian mining and working,
    - trade,
    - population growth,
    - irrigation, and
    - religious tourism
     
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