We have pleasure in presenting to readers this unique book which forms the collection of papers presented by eminent scientists and oriental pandits on Perception.

Of late there is a healthy tendency on the part of scientists all over the world to study and recognize the vast deep and original knowledge our traditional sastras contain. Therefore an effort was made to bring the scientists and pandits together to exchange their views and arrive at a consensus. This was a seminar arranged by the bengin blessings of their holinesses Sri Abhinava Vidyatheertha mahasanndhanam and Sri Bharathitheertha Sannidhanam the jagadgurus of sri Sharada peetam Sringeri.

The idea was conceived by Swami Paramananda bharathi a scientist in his purvasrama with deep understanding of both modern science and sastras. Under his able guidance authoritative and authentic views his able guidance authoritative and authentic views emerged from both the scientists and pandits. The Seminar revealed that many subtle points in sastras have remained under cover and the diverse philosophical systems in India might have much to contribute to our understanding of perception. This seminar on perception was held from August 15 to 18, 1985 at Sri Shankara Math Bangalore.

There was very good response from the public who attended the special lectures in the evenings in large numbers apart from a good number of elite attending the morning and afternoon sessions. This prompted us to present the papers in a book form which we expect will be received with acclaim.

We prostrate at the lotus feet of his holiness Sri Jagadguru Shankaracharya of Sri Sharada Peetham, Sringeri Sri Abhinava Vidyatheertha Mahasannidhanam who ahs graciously blessed our venture and has embellished this book with his benediction. We also offer our pranams at the holy feet of his holiness. Sir jagadguru Bharathitheertha Sannidhanam permanent trustee of our trust who benevolently permitted this book to be published by our trust.

Our pranams are due to Swami Paramananda Bharathi who has been the spirit behind the activities from organizing the seminar to publishing this book.

Editing a volume of this type was not an easy matter for the original papers were in three languages Sanskrit Kannada and English. A well knit group of scholars with command over all the three languages and the topic of the Seminar was present throughout the entire deliberations and rendered all papers discussions comments and views into English. Incorporating all this Prof. T.M. Srinivasan and Smt. B.G. Sreelakshmi have edited these proceedings. Their effort has been stupendous and we can not be adequately grateful to them.

The efforts put forth by the members of staff Sri Shankara Math for the Systematically and ably organized seminar are praiseworthy.

The director national Aeronautical Laboratory has lent us visual projection apparatus etc. we are thankful to him.

In conducting the seminar and compiling the papers the yeomen services rendered by a large number of volunteers deserve our gratitude.

Our thanks are also due to M/s Elgee Enterprises Bangalore for having printed the book excellently.

We consider that our efforts will be complete and successful if the readers can get an insight into our sastras and a quest begins in this direction with earnest.

Darsana Sastras are six: (1) Nyaya, (2) Vaisesika, (3)Samkhya, (4) Yoga, (5) Mimamsa and (6) Vedanta. Among these, only the vaisesika makes the study of nature as its main concern, though others also deal with it when necessary. However, one axiomatic thought common for all of them is the following:

The whole creation is ultimately intended for the experience of the Soul. (The word Soul is used in its popular meaning but will be clearly defined in the sequel). This is also the belief of modern physicists. Only they have not elevated it to the status of an axiom and derived its consequences as is done in the Sastras. The lead that the Sastras have taken over others because of this postulation will be envied even by the modern physicists. It is this: they were able to study the combined system, viz., the observed and the observer, even from the start. Here I am using the word observer with the same meaning as used by von Neumann[1]. It may be a measuring Instrument or more inwardly, the sense organs or the brain and so on. That is, as we go inwards, what was previously the observer later becomes the observed. philosophically this feature of the observed and the observer is of seminal importance. It may also be noted in another way: a length is measured by a scale which is only another length. The other length is an immutable length which does not undergo any changes due to either internal or external agencies. Similarly, a weight is measured only by another immutable weight and so on. Thus the observed cannot be of an entirely different category than the observer. If it were, it cannot be observed at all [2].

tatra yadyadatmakamindriyam visesat
tattadatmakameva, artham anugrhanati tatsvabhavat

Further, the axiom of the Sastras mentioned above also leads to the conclusion that nature, as perceived through the senses, can have only the five divisions corresponding to the five senses. These are the five elements they speak of: akasa (ether), vayu (gas), agni (light), ap (liquid) and Prthvi (solid) for which the respective sense organs are ear, skin, eye, tongue and nose. The correspondence that is envisaged here is that the two members of each pair of the observed and the observer belong to the same category. This classification called Pancikarana is the basis of ancient Hindu Physics and is based on direct perception. It is in exact opposition to the methods of modern thought which goes on subdividing matter into molecules, then into atoms, then into nuclei, then into elementary particles and so on endlessly. Even after accepting this classification of Pancikarana somewhat similar effort has been made by the vaisesika school[3] without success[4]. Nature is already too complex and so it is better to try to understand it on the basis of the perceptible classification on Pancikarana rather than add to the complexity by contrived subdivisions. Such a 'divide to know' policy can yield only a time-dependent knowledge of nature, since it rests exclusively on the cleverness (or, sometimes even the authority!) of the scientists at that time[5].

Among these five sense perceptions, touch and taste are mediated by direct physical contact of the observed and the observer. of course, it is necessary that the manas (mind) be tuned to the information input coming from the sense organs. This tuning in of manas is referred to as its 'contact' with the sense organ. Only with this contact, manas takes the 'image' of the object and this experience is called perception. Actual verification of perception by direct contact of the objects with the sense organs of touch and taste, now enables the guess that other perceptions also need such a 'direct contact'. Working on this guess, the Sastras conclude that the smell of an object is mediated by molecules of the object[6]. Therefore it is also by 'direct contact'. When this guess is verified by experiment, 'perception by direct contact' is exalted to an axiom.

The next step would be to incorporate this 'direct contact' axiom in the case of auditory and visual perceptions. But before this, we need to know why it is necessary to incorporate it. A physicist would say that the scattered light from an object interacts with the eye with which mind is tuned and so the retinal image would lead to perception of the object. Similarly he would say the sound vibrations would impinge on the eardrum and its corresponding vibrations would give the auditory perception. But Sastras raise an objection to this explanation: they say that in this way, the observer should get the perception of the retinal image or the vibrations of the eardrum and not the external objects or external sounds! When one looks at a clock, it is not the case that he perceives the moving wheels and springs inside and not the moving hands outside. Therefore, visual and auditory perceptions must also be transacted with 'direct contact' of the mind with the object through the indriyas (sense organs)[7].

tatraikam sparsanamindriyanam indriyavyapakam
Before analysing the nature of this 'direct contact' we consider another question. It is the following: From where the initiative should come for this contact? Is it from the object or the observer? It cannot be from the object, say the Sastras, since the objects are inert. Even by definition everyone knows that there is no inertia where initiative is and no initiative where inertia is. Initiative exists only in intelligence. So it can come from the observer and not from the object. The scattered light from an object may fall on the eyes, but still the object may not be seen. Only when mind takes the initiative and 'touches' the eye indriya the necessary process for perception starts. The pupillary aperture of the eye undergoes rapid oscillations, each configuration of the aperture being better suited to receive the image than the previous and the oscillations go on till the best image is obtained under the conditions. That is, the indriya processes the input information. This process is too fast and is not generally noticed. However, it can be observed with the help of appropriate instrumentation.

But is it not true that when the input signal is a bit strong, it provokes perception? So, can it not be said that the initiative is from the outside signal? No, it cannot be. Indeed, the strength of the signal is not even relevant here. Consider the situation when the signal is outside the range of normal perception.

Then the observer searches for it with refined instruments, if necessary. Moreover, if one is clinically unconscious, perception is impossible however strong, the input is. But normally, mind is outwardly and is ever ready to receive outside information[8].

Perception of the environment is necessary for the survival of living organisms. Even a single- celled amoeba reacts to stimuli, assimilates food from the environment and survives. A more complex organism has more complex processes that extend from its centre to periphery. A network of neurons, popularly called nerves, interconnects all portions of the periphery to the centre. As the periphery became complex during evolution, different specialised receptors evolved, some sensing the light energy, others respectively sound, touch, smell and taste. All these complex signals are carried to the brain which is the central station, through the spinal cord which is a bulky cable system. As the brain became complex, the number of neurons or nerve cells proliferated with tremendously large number of interconnections between themselves and with the periphery, making the brain larger and larger. The humans seem to have the largest-sized brain in comparison to the rest of the body. One may define the direction of evolution by considering the weight of the brain of different species in relation to their body weight. The humans by far outstrip all animals in this respect. The qualities of speech, mentation, idea generation, appreciation and interaction with the environment etc., seem to be in abundant measure in humans.

In all these interactions, perception plays a prominent role in conveying information from the environment to the person. Sensory perception provides an enormous amount of information to the brain of an individual during every moment of his/ her existence. The current theories in physiology are based on extensive research on animals and humans and many interesting details in this area are elucidated. However, it should be realized that many intriguing phenomena in perception have not been explained presently in modem science. We shall survey the current concepts in sensory perception, the psychology of perception and some of the outstanding problems that need elucidation. The papers that follow, summarize these ideas and suggest possible extensions of the theories necessary for understanding these phenomena. An introduction to these papers is provided below.

The first paper by Dr. Lord presents the various sensory modalities, the sense organs of sight, hearing, touch, smell and taste and the nerve connections to the brain. The external stimuli in the form of physio-chemical energies impinge on the body and stimulate the receptors which carry this information to the brain. A large number of specialized receptors cover the body surface, each one dedicated to a specific function. For example, there are different receptors for heat and cold, for pressure and for different taste sensations etc.

These raw signals are electro-chemical in nature and depending on the sensory mode, a certain amount of processing is carried out by the sensory organs themselves. This is true for the eyes and, to a certain extent, for the ears. The inputs are carried from the periphery to the brain by the nervous system through an intricate electro-chemical process whose details are well known presently. Specific areas in the brain are devoted to specific sensory appreciation. However, the integration of the sensory input which is ultimately responsible for the appreciation of the external world is still unexplained. How the brain interprets the upside- down image it receives from the retina of the eyes or how the brain appreciates different tonal qualities or fixes the position of the source of sound etc., is not fully known.

In the second paper, Sri N. Krishnaswamy deals with the details of visual perception and visual illusions. Being a vital sensory organ for survival, vision has come under intense study by many research groups. Unlike the ear which is also an organ of distant perception, the eyes are aware of the fields of view rather than just the vision of right and left sides of the person. In other words, the right eye may be thought of as consisting of two halves, the right half gathering information from the right field of view and the left half, from the left field of view. Similarly, the right half of the left eye is sensitive to the right field of view and the left half of the left eye is sensitive to the left field of view. These inputs are again combined in the brain in an unknown fashion to present the details of the external world to the person.

Also the psychology of perception is an unchartered territory. Several illusions abound, natural and man-made. Illusions arise because objective perception is prejudiced by our previous knowledge of the object. That is, the brain sees what it is used to and what it wants to see, rather than the actual details present in the object. Skewed images of rooms are not seen if an object of comparison is presented; rotating objects (such as windows, which in actual experience do not rotate) seem to open and close etc. Hence, sensory perception and appreciation have a strong component of previous experience and present reference frame in which perception takes place. The brain also fills the missing portions of an incomplete image based on its previous experience. Thus, for a complete experience, one has to take into account the psychological or mind-related processes also. Even emotions of anger, elation etc., playa vital role in the process of interpreting the raw sensory data.

In his paper, Dr. H.S. Subramanyam deals in detail with the psychology of perception bringing more ideas to bear on the mind-related experiences of perceptual information. Attention and motivation become very important factors in the perceptual process. As we go deeper into the psychological processes of perception, modern science is still vague and indefinite. The intricate processing that goes on in the brain, the 'tuning in' of the mind to brain processes, the extraction of information even in a very noisy environment, the 'filling in' of details by the brain of an incomplete image, the comparison of incoming data with already available information, total integration of all inputs resulting in an appropriate response of the entire organism to the input stimulus - are all still under investigation in the psycho-physiological laboratories round the world.