It piqued my curiosity, so I tried it for myself - three times. And each time I got the same result.
I put in additional "controls":
- I cooked the rice in water and salt, and added nothing else.
- I sterilized the jars and lids to reduce contamination.
- I put the rice in the jars as soon as it had finished cooking.
- I was careful to put equal amounts of rice in each jar (or as close to equal as I could get).
- I made sure the lids sealed the jars tightly.
- I put the three jars together on the same small table in my kitchen.
- Each time I did the experiment, I changed the position of the jars - just in case!
Here's what I found:
- The rice in the "thank you" jar grew a white, fluffy mould.
- The rice in the "you fool" jar grew a darker, heavier mould.
- The rice in the jar I ignored grew an almost black mould - and moulded more quickly than the other two.
The next time I try this (as I'm sure I will), I won't actually say anything; I'll just think it. And when I do, I'll let you know what happens!