Planta Sapiens by Paco Calvo

Author:Paco Calvo
Language: eng
Format: epub
Publisher: W. W. Norton & Company
Published: 2023-01-27T00:00:00+00:00

Figure 4: Example of size constancy: a texture gradient formed by cobblestones with two bricks. The space occupied by the bricks is the same with respect to the area being covered.

How do you explain size constancy ecologically? Your optical system and brain don’t go through the rigmarole of computing distances and inferring brick sizes. They have no way of collecting that information, for starters—we are not machines equipped with speedometers and tape measures. Another type of information which is just as useful is directly available at the retina itself. Notice that the percentage of cobblestone occupied by each brick is the same: both bricks cover about a third of the cobblestone they stand on. Regardless of the different distances and the projected sizes on the retina, it is the ratio of brick width to cobblestone surface that provides the clue which allows your brain to understand that the bricks are actually the same size. It’s not absolute length and distance that we build our perception from. Instead, it is the relation between objects and their environment that we use.

The imaginations of science fiction writers can sometimes throw up scientific insights and predictions. Hoyle was a bit of an ecological astronomer. His characters used the sensed ratios to work out the cloud’s movement, and how long it would take to arrive. Picture the cloud as a basketball being thrown at you (Figure 5). The distance between the ball and your eye is decreasing rapidly. Let’s assume that at time t the basketball is at z(t) distance, and that it approaches at a constant speed. The image the ball will project on your retina will have a size, r(t), that is proportional to the real size of the ball. As the basketball approaches you, its image will grow at v(t).8

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.