Subliminal perception is one of the most controversial topics in psychology. Since the appearance of the first experimental work on the subject, carried out by Suslowa in 1863; Hundreds of empirical investigations were carried out, the results of which contributed to the controversy over the very existence of subliminal perception as a real psychological phenomenon.
Those who do not admit that the human being has the capacity to respond to stimuli of which he is not aware, argue that subliminal perception is an artifact, an artificial product of psychological experiments.
Fuhrer and Eriksen consider that even in the impoverished conditions of stimulation in which subliminal experiments take place, the subjects consciously perceive portions of the stimulus material which determine their responses in such experiments.
From the other extreme of the controversies: the possibility of an unconscious registration of certain external events (stimuli that remain outside the consciousness) is admitted, which can influence conscious cognitive activity.
1) BASIC CONCEPTS AND SUBLIMINAL STIMULATION TECHNIQUES
The idea of an unconscious perceptual processing of external stimuli can seem a bit disconcerting since perception is usually considered as an experimental event, that is, a process that is carried out through our senses and in a conscious way.
Probably for this reason some psychologists consider that the term subliminal perception was inappropriate. Thus, for example, Klein speaks of "subliminal register". According to this author, the concept of perception would always imply a conscious knowledge of the identity of a stimulus or its meaning.
However, at present, the notion of perception as a unitary process that necessarily involves a certain degree of consciousness tends to be abandoned, and perception tends to be conceived as a process that encompasses a series of stages or phases of processing of information coming from external stimuli, much of which takes place outside of consciousness.
Subliminal perception can be defined as: a process of extraction and analysis of information from stimuli of which the subject is never aware.
This total absence of phenomenal representation of a stimulus becomes evident when, for example, the subject is unable to verbally report the very existence of the stimulus. These stimuli that never reach consciousness are subliminal messages. The intensity or minimum exposure time necessary for the detection (conscious) of the presence of a stimulus, is known as the threshold of consciousness. At this level, the only thing that subjects can report is that they saw or heard “something” without being able to identify exactly what it is.
Those stimuli that are above the threshold of consciousness are called supraliminal stimuli.
A) TYPES OF SUPRALIMINAL MESSAGES
• UNATTENDED MESSAGES: those that are not consciously perceived because the subject does not pay attention to them, and they can be brought to consciousness by the simple act of attention, whereas subliminal messages do not.
• UNDER-RECOGNITION MESSAGES: those that are below the level of intensity or exposure time necessary for the correct identification of the stimulus.
• RECOGNITION MESSAGES: those stimuli whose intensity or duration are sufficient to allow the correct identification of them by the subject.
B) SUBLIMINAL STIMULATION TECHNIQUES
In subliminal experiments, various stimulation techniques are used, the objective of which is to prevent conscious awareness of the stimuli by the subjects.
• MASKING: this technique consists of the presentation of a fleeting stimulus "A", immediately followed by another of longer duration "B". For example, Smith, Spence, and Holt presented the drawing of an emotionally expressionless human face preceded by very brief exposures of the words "happy" and "angry"; the result was that the subjects tended to perceive a "happy face" when the expressionless face was preceded by the subliminal word "happy".
• DIRECT IMPOBRECIATED STIMULATION: consists of the direct exposure of a stimulus below the threshold of consciousness or recognition and the subsequent execution of a specific task. The type of responses of the subject to this task will show whether or not there was a non-conscious record of the stimulus in question.
• EMBEDDING: this usually consists of inserting the critical stimulus (such as a word or a figure) in the context of a more complex visual material (such as a photograph) in such a way that it cannot be perceived at a supraliminal level. Therefore, critical stimulus would be camouflaged in the material that is presented to the subject. This technique is widely used in the field of advertising.
• DICOTIC STIMULATION: this technique consists of the simultaneous presentation of subliminal and supraliminal stimuli (auditory or visual) through different channels (auditory or visual).
2) EXPERIMENTAL EVIDENCE:
a) Groeger (1984) in order to find out if the identification of a stimulus is a prerequisite for its semantic analysis, individually presented to a group of experimental subjects a series of words, critical words, below the threshold of consciousness and, continuation of each word, for two seconds, an array with words randomly placed in each of its 24 cells. These words were semantically or structurally similar to the critical word. For example, for the critical word TOWN (town), a semantic alternative would be CITY (city), and a structural alternative would be FLOWN (exalted). The procedure was then repeated exposing the critical words to an underrecognition level. The same procedure was applied to a control group except that instead of critical word a white field was presented.The subjects were advised that a word would be presented very quickly and that their task would consist of selecting from the matrix that word that they thought had been previously exposed.
The results of this experiment indicate that subjects frequently choose the semantic alternative in the subliminal condition, the structural alternatives in the sub-recognition condition, and both alternatives equally in the control condition. This suggests that the subliminal stimuli receive a predominantly semantic processing, which would not affect the alternative of a structural choice and, in the same way, if there was a structural processing at the subliminal level, it would not influence the choice of a semantic alternative.
This question of the differential processing of stimuli as a function of their level of consciousness was made evident in the work of Somekh and Wilding. These authors observed that at the supraliminal level, the words “happy” (happy) and “sad” (sad) as well as their structural equivalents “harp” (harpy) and “sap” (fool) affected the conscious impressions of a face emotionally expressionless. At a subliminal level, exactly the same thing happened but only in the words “happy” and “sad”. That is, in the first case, the subjects respond to “harpy” and “sap” as if they were the words “happy” and “sad”.
Apparently these stimuli phenomenally not present in consciousness, can influence some aspects of our behavior.
Potzl was the first to demonstrate the influence of subliminal stimuli on the content of dreams. This researcher presented a subject for fractions of a second, a landscape and asked him to describe and draw what he had seen. Those parts of the stimulus material that he did not represent at the time appeared later in the drawings and descriptions he made of his own dream the next day.
In short, the meaning of a stimulus can be registered outside of consciousness and consequently affect conscious cognitive processes.
In the area of memory Holland and Spence observed that the subliminal exposure of the word "cheese" tended to skew the memory of the subjects towards those words semantically associated with "cheese". This predominance is due to the fact that the subliminal stimulus produces an activation of a set of meanings related to it, which would facilitate the memory of the semantic associates of a list of words.
3) SUBLIMINAL MESSAGE IN ADVERTISING
The problem of subliminal perception reached a huge public repercussion in the fifties due to the fact that a commercial company released a study on that date in which supposedly the subliminal exposure of the words "eat pocholo" and "drink coca-cola" in the course of a movie program it had the effect of increasing sales of these products.
The effectiveness of subliminal stimulation in advertising is a highly debated issue and not yet sufficiently demonstrated. Thus, for example, Key maintains that the subliminal messages inserted in certain advertisements influence consumer preference for certain products. In contrast, George and Jennings found that subliminal exposure of a brand of chocolate did not alter the drinking patterns of the experimental subjects.
These subliminal effects can be enhanced or completely disappear by the action of a certain number of factors: personality structure, biological needs, cognitive predisposition, state of consciousness, etc.
Personality dynamics and perceptual process
Our purpose is to show the independence that exists between the dynamics of personality and the dynamics of perception, a theory of personality cannot be completed without a theory of perception that completes it.
Through the work of Frenkel - Brunswik herself, as well as through Klein's research at the Menninger clinic, they have dealt with the variables of personality and their manifestation in the perceptual field. It begins with the concept of rigid personality and seeks if it manifests itself and in what way in functional areas such as thinking, perceiving, remembering, etc. A preliminary study showed that personality can be characterized, in terms of basic guidelines, as authoritarian and rigid personality (inclined to exhibit ethnocentric attitudes) and at the other extreme, as flexible and tolerant personality.
Sketch of a theory of perception
We are looking for a suitable theory for the laboratory as well as for the clinic, the theory we are looking for must contain in itself the possibility of handling the differences in perception that characterize the different constellations of the personality. A theory of perception oriented towards the personality, needs precisely the laws to explain the judicative and perceptual-systematic tendencies of different groups of people with different personality patterns. During the last years they have been inclined towards a theory of perception as a phenomenon of expectation or of hypotheses as being the most suitable to work in both fields, the experiment on perception in the laboratory and clinical observations.
The broad lines of the theory involve a three-stage cycle.
• Analytically we can say that perceiving begins with an expectation or hypothesis, what is it that evokes a hypothesis? Any given hypothesis arises from the appearance of central cognitive and motivational processes derived from the preceding environmental situations.
• The second analytical step in the perceptual process is the input of information from the environment (a medium that includes the complex of stimuli brought by distance receptors and somatic senses)
• The third step in the cycle in a verification or confirmation procedure, the incoming information confirms, or is consistent with the operating hypothesis. If confirmation does not occur, the hypothesis is modified in a certain direction.
About the information cycles that they constitute, the perceptual process can be classified into three large categories.
1. Questions about the characteristics and dimensions of the hypotheses or expectations that characterize the first state of perceiving and the conditions that promote hypotheses of different types.
2. Questions about the nature of the information that may or may not confirm a given hypothesis.
3. Questions about the process by which the hypothesis is confirmed or weakened or altered.
The nature of the hypothesis
The concept of hypothesis can be compared with terms such as determining tendency, disposition. It can be considered as a highly generalized state of predisposition to respond selectively to classes of events that occur in the environment.
In theory, a hypothesis is inferred, of course, from the presence of certain preceding and consequent facts, for example prior instruction and consequent threshold reduction. A hypothesis is not limited in any sense with respect to the substantive nature of its selectivity, it may be selectively tuned for the perception of colors of a certain hue but more often it is tuned for the perception of environmental attributes.
Hypothesis strength
A basic property of the hypothesis is the one we refer to as force, there are three possible theorems in this concept of force.
1. The stronger a hypothesis, the greater its probability of arising in a given situation.
2. the greater the strength of the hypothesis, the less is the sum of appropriate information necessary to confirm it.
3. The greater the strength of the hypothesis, the greater the amount of inappropriate or contradictory information necessary to weaken it.
Let's see what is necessary to define more precisely how we infer the strength of a hypothesis and how we know how much appropriate information has been necessary to confirm it.
• Frequency of past confirmation: The more frequent a hypothesis or expectation has been confirmed in the past, the greater its strength.
• Monopoly: The lower the number of alternative hypotheses regarding the environment that a person has at any given time, the strength will be. A monopoly hypothesis is stronger than the bipolistic hypothesis, the closer a hypothesis is to the monopoly, the less information will be required to confirm it.
• Cognitive consequences: The greater the number of sustainable hypotheses or the more integrated the sustainable hypothesis system, the stronger the hypothesis.
• Motivational consequences: The more basic is the confirmation of the hypothesis to lead to an activity that tends to an end, the greater its strength. It will arise more easily, it will be confirmed faster and less easy to weaken it.
• Social consequence: Where stimulating conditions are such that the information, either to confirm it or to weaken a hypothesis, is minimal, the hypothesis can be strengthened by virtue of its agreement with the hypotheses of other observers to whom the perceiver may turn.
Nature of the confirming information or weakening you
We first distinguish between relevant and non-relevant information; revealing information or revealing clue, refers to incoming stimuli that can be used by subjects to confirm or weaken an expectation about the environment. The simplest case occurs in the area of perception of space. Certain information such as prospect lines are clearly relevant as a starting point to confirm or weaken a hypothesis that refers to the distance of a hay stack in the valley. Other signs are not relevant: the heat of that day, sound, etc. Among the relevant evidence, a hierarchy of reliability can be distinguished. The aspect of the terrain, particularly in circumstances in which we do not clearly recognize the composition of the region, is a relevant item of the stimulating information, although not very reliable.The apparent size of a haystack in an area where we do not know the characteristic sizes of haystacks, is also an indication of relevant but not very reliable information.
We have a continuum that goes from relevant and reliable information through relevant and unreliable information, to non-relevant information.
We must distinguish between the definition of the relevant and reliable information of the experimenter and the use of the information by the subject. This is the essence of any experiment that we define in advance what we as experimenters understand as relevant information and not pretend that the subject's response does, that is, we set the criterion that it is a correct perception, when he has used what we we have defined as the relevant clues to arrive at the final opinion that is in front of him.
What is studied in most of the perception experiments is the dimension in which the subject is able to fly over the relevant signs (defined by the experimenter) to confirm and / or weaken the hypothesis, this over valuation depends on the type and strength of the hypothesis that the subject uses in his perception of the situation; if our subject has a strong religious orientation and is inclined to focus his perceptual environment provided with hypotheses concerning religious behavior, he will quickly reconstruct the rest of the stimulus in terms of his religious hypothesis.
Consequence for a theory of personality
A personality-oriented theory of perception must have systematic means by which it can account for individual differences in perception. We will mention two important points whose articulation can and is being done with a theory of personality and a theory of social behavior.
1. Differences in the types of hypotheses that different individuals habitually employ reflect differences in past history, in personality structure, and so on.
2. Difference in the strength of the hypotheses that characterize different individuals, again reflects divergent histories and the most marked tendencies of the personality.
Taking these points into account, we return to the material deduced from the work of social psychologists and theorists of perception on the functioning of the personality. We have to consider the issue of culture as a very influential issue in personality.
The selection of prominent personal clues
There are two guides for the selection of personally outstanding stimuli for research, one is theoretical. Various theories about personality contain implicit or explicit assertions concerning cues from the environment that guide the individual in maintaining or improving her personal adjustment.
Another approach to selecting relevant clues to study from the point of view of acceptance is frankly phenomenological. We begin by inquiring how the world appears to us. The answer to such a simple question would be that the world consists of many things, possibly divisible in our perception, such as me, objects and people. We could propose that the variations to the stimuli of the perceived self provide the most highly relevant stimulus information to confirm relevant hypotheses from the point of view of adaptation, that is, hypotheses whose confirmation is crucial for adaptation.
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