FROM EDITION 9 OF THE TRADITIONAL AIKIDO EUROPE JOURNAL – WINTER 2023
Let us look at this question in three parts: first for solo practice, then for practice with a partner, then in movement, specifically when dealing with multiple attackers. As a supplement there are some neuro-physiological explanations about the visual process at the end of this article.
1. Solo Practice
I found this text from a Iaido blog:
“An important element of going beyond the mechanics of the form, is sighting your opponent; i.e., looking in his direction and fixing your gaze wherever he may be. Many books on swordsmanship simply say that the beginning iaidoka should fix her gaze towards the floor two metres ahead, but once the mechanics of the kata become more familiar, her gaze must be levelled at her imaginary opponent.” 
This passage refers to iaido solo kata but can be applied for katas in aikido as well. I would argue however that already at beginners’ level the gaze should preferably be levelled at the imaginary opponent, or else a strange habit is ingrained. Often, I see students perform solo kata putting their gaze too close in front of themselves on the floor. Because the body tends to follow the eyes, this affects their whole posture, their back getting rounded, shoulders tight, often balance lost towards the front and all in all their movements getting too contracted. Just a short comment, like ‘lift your gaze’ can change their whole practice completely. Practising any kata every once in a while in such a way that after each movement the pause is increased to check the form, starting from the gaze and then downward can help change habits in this regard. So next time you practise the 31 or the 13 jo kata, or any kind of solo kata – also tai sabaki – pay attention to what you do with your eyes.
2. Partner practice
Now let’s look at partner practice: ‘level the gaze at the opponent’ still is quite a vague description. Should we look at their head? At their eyes? Their hand, feet, weapon?
Wherever you put your eyes, there is also the tendency that your mind will move there.
‘If you send your mind in one direction, it lacks the other nine. If the mind is not restricted to one direction, it is in all ten.’ Takuan Soho 
Rather than focusing the eyes on a certain part of the attacker’s body – or their weapon – our gaze is directed to the chest area of the attacker, but not focusing there, rather zooming out as if we wanted to see something more in the distance. “Enzan no metsuke”, translated as ‘looking into distant mountains’ is the term often used in martial arts referring to this. The feeling is a ‘softer’ gaze that envelops the partner.
In this way we get less distracted by unimportant visual information (e.g. colour and pattern of clothes) and can ‘see’ more easily the origin of the attack.
At first one might see the attack coming only if the attacker is helping us with big, slow attacks. But with increasing experience the signs of an attack can be read more easily and by this we ‘gain time’ to respond to them. Eventually it will be possible to ‘see’ the intention before the attack.
In karate or also kendo the term metsuke refers to using your eyes. "me" means eye and "tsuke" means to attach. Literally speaking: attach your eye to your opponent. Not letting him or her out of your sight. There are two levels of metsuke: Ken No Me and Kan No Me.
Ken no metsuke: This is translated as ‘to look, see, watch’ with your eyes. To look at the attacker, see how they are moving. And then respond accordingly.
Kan no metsuke : Can be translated as "to observe the truth." Not only to see, but also to understand what the opponent will do next. Thus, not just by looking through the eyes, but rather using the mind, intuition, insight or instinct. With years of practice and experience the senses and feelings have been sharpened. How fast kan no metsuke is achieved largely depends on personal talent in sensitivity and analysis. As a beginner it is not something to worry about, but definitely something to strive for.
When attacking, the eyes are focused on the target (head, hand, knee….). But only for a split second (together with the ‘kime’) and then the gaze should be opened again to be ready for responding to partner's reaction. We should not get fixed on the target, or else we will be late for the next move.
In the special case of attacking the knee: be careful not to focus ‘down’ too much, or else you will signal your attack.
The gaze can also be used as a ‘feint’ to distract the opponent and attack by surprise. E.g. to look at the left shoulder and attack the right knee. Of course, this only works against someone who hasn’t yet internalised the approach of the soft gaze as described above.
Have you ever assisted a child learning to cycle? It was certainly more helpful to show them the direction they needed to steer towards, than showing them the curbstone that they must not hit….: The eyes lead, the body follows.
Whether it is in solo practice and you want to turn with a tenkan or kaiten, or when dealing with multiple attackers, we should always first direct our eyes, and with them our head, in the direction we want to turn. The rest of our body will follow more easily.
There is a tendency to be stuck with the eyes on the attacker, e.g. the one grabbing us. Especially when dealing with more than one attacker, this will cause a problem. But we know exactly where this attacker is: he is grabbing me. Rather, I should turn and look out for the other attacker(s), ideally while at the same time moving out of the grip. This is exactly what’s happening with kotegaeshi for example: turning away from the partner in order to see the other(s) and with the turn freeing myself from the grip.
In tai no henko we are constantly reminded to turn completely and look the same direction the partner is facing. In morote dori kokyu ho we tend to forget this again, not turning completely and ‘running ahead of the technique’. Why? Because our evolutionarily ingrained reflex of keeping our eyes in the direction where the problem / danger is, makes us stuck with our head turned only midway (‘maybe I can still see him peripherally?’) and so also our hips only turn midway, resulting in not taking partners' balance properly. Also in this case, from a teachers’ perspective, rather than correcting the hip movement it is mostly enough to instruct to turn the head completely.
The physiology of seeing (Geek alert):
The visual field refers to the total area in which - without movement of the eyes or the head- visual perception is possible. It has a binocular (stereo) extension of about 120° horizontally.
The visual field is composed of foveal (or focal) and peripheral vision. In foveal vision, the central axis of the eye is precisely aligned with a targeted object for a maximum central visual accuracy. Peripheral vision involves "seeing past" the object in question. This provides coarse, blurred and optically distorted visual impressions of objects in the visual field. But when we look in the distance, our eyes diverge slightly, thus increasing the active visual field.
Clear recognition is only possible within the central area, the fovea; the quality of perception in terms of visual acuity, pattern recognition and colour vision decreases, the more peripheral the visual stimuli are. Sensitivity to moving objects also decreases peripherally, but less so than other visual functions, so that in peripheral vision there is a relative superiority of motion vision over other visual functions. The periphery of the visual field is therefore particularly important for recognising dangerous situations.
When adopting a peripheral vision ‘looking’ at a partner in front of us, we may not be able to distinguish colours and patterns on their shirt or the length of their nose, but we will still see movements, not only from the partner ahead of us, but within the whole visual field.
Visual processing describes the brain’s ability to understand and process what the eyes see. It has been suggested that we distinguish two types of processing: the focal mode and the ambient mode. The focal mode uses almost exclusively visual information, while the ambient mode includes information from the vestibular, somatosensory, and auditory senses to assist spatial orientation, posture, and gaze stability.
Focal and ambient modes differ in a number of ways. While the focal mode requires adequate light conditions, ambient mode still works well also with degraded image quality or reduced light. Focal vision typically involves attention, while ambient visual functions are more reflexive in nature. We can therefore, for example, read a book (focal mode) while we walk and spatial orientation (ambient mode) is still maintained with no conscious effort.
Under stress, tunnel vision can occur, where objects imaged in the peripheral visual field may not be detected at all. Ambient vision, which does not require attention, is probably unaffected by this attentional narrowing.
In practice: Based on this information, and from my own experience I would hypothesise that with practice we can train to use our peripheral vision more and we can also train to pay more attention to our ambient mode of processing. So that, even under stressful circumstances, tunnel vision will not occur.
How do we do this? Training under adequate stress levels, increasing them over time, in order that also in critical situations, we manage to stay alert, but calm. ‘Artificial’ stress specifically directed to our visual system would involve training in (semi-)darkness. With the help of purposeful practice, you can achieve the skill of subtle perception of the opponent’s body movements, including invisible ones, and thereby anticipate his intentions and actions.
Maybe this relaxed, alert peripheral vision is the ‘kan no metsuke’ as described above.
 Zen master Takuan Sōhō (1573 – 1645) in a letter to sword master Yagyū Munenori, quoted from: The Unfettered Mind: Writings of the Zen Master to the Sword Master, translated by William Scott Wilson