Case Study:
1 min 7 sec: Plants respond to touch or proximity
This is a common assertion by artists (Masaoka, 2002) (Mileece, 2012). Although it is well known that Mimosa Pudica (the sensitive plant) and Dionaea Muscipula (the Venus Fly Trap) generate action potentials when touched and others may do as a resulting in thigmo-tropism (Burdon-Sanderson, 1873), in most cases the readings artists are taking are not the result of a reaction in the plant at all. What is really happening is that the human body’s own electrical field is using the plant as an earth, so the electrodes are really responding to electrical field of the person touching the plant and are not reading a response in the plant at all. In fact, you can get the same results by touching a piece of damp cloth with the same two electrodes in it.
As one plant electro-physiologist put it:
“Earthing may be not the best term but yes it is an artifact , when you approach or touch the plant, you are changing its capacitance, and this is picked up and amplified. Nothing to do with what the plant’s sensing “ (Shabala, 2013)
Another electrical engineer explained :
“What is really happening is that when touching the plant a current path is created between the plant and the body and this can lead to an alteration of the plant’s electric field. Consequently the electrodes are responding to this variation and are not reading a response in the plant at all.” (Massi, 2013)
In scientific experiments a plant is usually put in a faraday cage to ensure there is no electrical interference from the surrounding environment (Jörg, 2007) Please see included video “correct way to read action potentials in plants”. In such laboratory experiments it is a cardinal sin to touch a plant as it is well known that the human body’s electrical field will affect the readings. Proximity to a plant can also cause a change in the readings for the same reason. Sometimes, such as in the cited video, it is claimed that plants exhibit different strengths of electrical response depending on how hard or softly you touch them (Lepp, 2013); again this is simply because the harder you touch something better contact there is between the skin and surface being touched.
However as mentioned, plants do respond to touch and this is known as thigmo-tropism whereby plant growth is affected by touch (Mordecai, 2002). New research also reveals changes in gene expression minutes after a plant is touched (Van Aken, 2016). However, these are completely different phenomena. In general it is advised that you avoid touching plants or even going near them if a faraday cage is not being used as despite the seemingly dramatic response it provokes in electrode readings, as this is misleading and deprives the artist of an opportunity to present the true electrical processes happening within the plant. If a faraday cage is not desirable then as much electrical activity in the environment as possible should be removed, the plant should be kept well away from any mains current, and equipment such as laptops should run off battery power if possible . Filters which remove 50 Hz and 60 Hz (mains) should also be used in all cases – some electro-physiologists recommend a low pass filter as low as 20 Hz, while others recommend band stop filters .
1:20 The plant appears to respond to sound
It is not clear here that this is happening at all and in the short part of the video that does show a response to the sound of a hand clapping, the hand is seen to touch the plant. Again the proximity of the hand to the plant may elicit a change in capacitance as well.
1:35 Plants are responding immediately to changes in light
Although this may be possible, usually these fast dramatic responses to changes in light displayed by some artists are usually a result of the measuring equipment being on the same ground loop as the lights – so turning them off or on results in a spike in electrical measurements and is misinterpreted as a response in the plant. Again filtering mains electricity is recommended and wherever possible run equipment such as laptops from batteries (separate from the light).
2.2.8 Aesthetics
Bearing in mind that all such judgements are subjective, aesthetically I found the sounds in the piece appealing and believe they would work as a work of art in their own right. However, one common theme in many similar works to this is that of plants in jars, surrounded by machinery and technology. From the perspective of my own artistic style I find this aesthetically displeasing. It seems to symbolise the idea, albeit subtly, of man’s domination over nature by means of technology. As a result of this I decided to make my installations a reversal of this aesthetic. I would conduct them in the field where the technology aesthetically was overwhelmed by the plants themselves, with an ultimate objective of combining the natural and the technological in one balanced hybrid system.