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Chapter I: Uniqueness of the Human Mind >> Mental synthesis definition and examples

Mental synthesis definition and examples

Mental synthesis is the central concept of this book. We will consider more examples of what mental synthesis is and what it is not, but first let us define the building blocks of mental synthesis: mental images.

Definition of mental image and visual percept

Normally, when your eyes are open, your visual image is formed by visual information coming from your eyes. Excluding hallucinations and ambiguous images, your mind’s image is more or less a direct representation of what your eyes see. We refer to this image as a visual percept (the perception formed by a visual input).

When you close your eyes, you stop the flow of visual information from your eyes. Now your mind can attend to any images from your memory or form entirely new images. By definition, a mental image is a picture arising in the mind when the eyes are closed. Sometimes non-visual properties are included into the definition of a mental image. We can talk about an audio image and about a tactile image. However, in this book, we will limit the definition of a mental image to a purely visual image. This will greatly simplify the logic of the book and avoid unnecessary confusion.

Thus a mental image is formed with closed eyes and a visual percept is formed with open eyes.

Definition of mental synthesis

Let us run a mental experiment. Close your eyes and imagine your favorite cup somewhere where you have never seen it, for example, the cup standing on top of your keyboard. Now open your eyes and let us discuss the events that took place in your mind. Your mind evoked an image of the cup from memory. Then it also evoked an image of the keyboard. Then your mind integrated images of the cup and the keyboard. That is, your mind synthesized a new image from the two images that were generated from memory. This is an example of mental synthesis.

Now, close your eyes and imagine that cup falling from the keyboard to the floor. To imagine the falling cup, your mind generated frames (mental images) of the falling cup. In other words, a series of images run through your mind like a movie runs in a movie theatre. Finally, the cup falls on the floor and brakes into pieces. Your mind has generated a new image of the broken cup.

By definition, mental synthesis is the process of synthesizing a new, never-before-seen image from two or more mental images. You have never seen a cup on top of a keyboard, but you can readily generate an image of a cup on top of a keyboard in your mind. If you, at some point, saw a cup on top of a keyboard and then were to recall the image (of the cup on top of the keyboard), the process would not involve mental synthesis, as you would just be invoking a single mental image from memory.

Mental synthesis versus mental imagery and imagination

Mental imagery is usually defined as the experience of perceiving objects or events when those objects or events are not actually present but occur in the mind. Mental imagery includes remembering of an object or an event. In other words, the process of mental imagery may not involve any mental synthesis at all.

Similarly, imagination is usually defined as image-making power of the mind that can include recall of images stored in memory. Mental synthesis is a subset of phenomena that can be described as mental imagery and imagination. The other subset includes memory recollection. Memory recollection and mental synthesis have distinct neural mechanisms as discussed in Chapter III. Memory recollection is evolutionarily older process that is natural to many animals. Consequently, mental imagery and imagination are bad descriptors for a candidate for a uniquely human trait. We need a narrower definition, one that excludes memory recollection. Thus we defined mental synthesis as the process that involves combination of two or more images with the result of producing a new image that was not previously stored in memory.

Mental processes that do NOT involve mental synthesis

Mental synthesis should not be confused with many other visual processes. Remembering a picture (creating a mental image of an object from memory) or remembering a sequence of images (a mental movie) does not normally involve mental synthesis (as you do not need to combine two representations together to recall images from memory).

Remembering an image that your mind had synthesized in the past does not involve mental synthesis either. Mental synthesis must include an active voluntary process of synthesizing a never-before-seen image from several images generated from memory.

Matching an object in the visual field to an object in memory or comparing two objects in the visual field does not normally involve mental synthesis. Even when matching requires scaling and rotation of one of the objects, the process may not involve mental synthesis. The fact that matching two objects in the same/different paradigm may be solved by humans in the process of mental synthesis, does not mean that the mind of humans always uses mental synthesis to solve this problem. In the course of evolution, nature has created a great number of shortcuts that bypass the energetically expensive and relatively slow process of mental synthesis. Often a solution can be obtained in a simpler, more direct process. You can think of these shortcuts as reflexes. Humans have a great number of reflexes and conditioned reflexes. When you touch a hot stove, you don’t need to think whether you want to withdraw your hand or not. You have a reflex that automatically withdraws the hand. When you step on a nail you don’t need to think about what to do next; you have a reflex that automatically withdraws your foot before the nail could puncture the skin. When an insect flies toward your eye, you instinctively close the eye. The body is full of reflexes and automated actions. When you play tennis, your mind does not need to imagine the trajectory of the racket. In fact, thinking of a racket normally prevents you from executing a perfect stroke. Playing a musical instrument or typing on a keyboard will become excruciatingly slow and difficult if you imagine every move of your fingers.

If so many visual tasks can be performed automatically without mental synthesis, then is it even possible to investigate the presence of mental synthesis in animals?