SEEING BLUE AS RED: A Hypnotic Suggestion Can Alter Visual Awareness of Colors

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1 Intl. Journal of Clinical and Experimental Hypnosis, 64(3): , 2016 Copyright International Journal of Clinical and Experimental Hypnosis ISSN: print / online DOI: / SEEING BLUE AS RED: A Hypnotic Suggestion Can Alter Visual Awareness of Colors Sakari Kallio University of Skövde, Sweden Mika Koivisto University of Turku, Finland Abstract: Some highly hypnotizable individuals have reported changes in objects color with suggestions given in normal waking state. However, it is not clear whether this occurs only in their imagination. The authors show that, although subjects could imagine colors, a posthypnotic suggestion was necessary for seeing altered colors, even for a hypnotic virtuoso. She reported posthypnotic color alterations also selectively in response to specific target shapes in briefly presented object arrays. Surprisingly, another highly hypnotizable person showed a very different pattern of results. The control participants could not simulate virtuosos results by applying cognitive strategies. The results imply that hypnosis can alter the functioning of automatic visual processes but only in some of the most hypnotizable individuals. Perception of color seems to be a paradigmatic example of an automatic process that occurs without any effort. When we open our eyes in normal lighting, we see the objects in front of us immediately in their full colors. Experimental findings, such as those concerning a pop-out of color (Treisman & Gormican, 1988) further support these notions. However, recent studies (Kosslyn, Thomson, Costantini- Ferrando, Alpert, & Spiegel, 2000; Mazzoni et al., 2009; McGeown et al., 2012) suggest that some individuals can change the perceived color of objects. Some of these studies (Mazzoni et al., 2009; McGeown et al., 2012) applied an imagery suggestion with and without hypnosis while the observers were viewing a Mondrian-like image (see Figure 1). Highly Manuscipt submitted May 11, 2015; final revision accepted November 8, Address correspondence to Sakari Kallio, School of Bioscience, University of Skövde, Högskolevägen, Box 408, Skövde, Sweden. sakari.kallio@his.se Color versions of one or more of the figures can be found online at com/nhyp. 261

2 262 SAKARI KALLIO AND MIKA KOIVISTO Figure 1. The gray-scale and colored versions of the Mondrian figure used in Experiment 1. hypnotizable participants reported alterations in color perception when instructed to add color to a gray-scale version of the figure as well as when instructed to drain color from a colored version. Importantly, these alterations (referred to as visual hallucinations in these articles) occurred both with and without induction of hypnosis. It was further observed, with concomitant functional magnetic resonance imaging (fmri), that neural activation in the color-processing areas was modulated by the instruction independent of hypnosis (McGeown et al., 2012). These results suggest that highly hypnotizable individuals may change their color perception in a normal state of consciousness by using mere attentional and imaginative skills. The results of these studies (Mazzoni et al., 2009; McGeown et al., 2012) on changes in visual perception imply that hypnosis does not play any essential role in color alterations. However, the following questions arise: What do the observers truly experience when they report color alterations in or out of hypnosis? Do the alterations occur only in their imagination or are the objects really seen in different colors? Do the altered color perceptions resemble normal color perception in the spontaneity and automaticity, which is its hallmark, or do they occur only with the use of effortful top-down imagination when the participants are asked to actively add or drain color? This question has a crucial theoretical importance since automaticity has by many researchers been argued to be the essence of hypnotic responding (e.g., Kallio & Revonsuo, 2003; Weitzenhoffer, 2000; see also Sadler & Woody; 2006). In contrast, the social cognitive theories consider hypnotic responding as being based on voluntary goal-directed behavior and imagination. The subjective feeling of automaticity is just a result or byproduct of purposeful cognitive processes (Lynn, Kirsch, & Hallquist, 2008). This view is further underscored by Kirsch and Braffman (2001) by advocating a concept imaginative suggestibility (to replace hypnotic suggestibility ) to stress that all hypnotic responding is about engaging in fantasies.

3 SEEING BLUE AS RED 263 Since the concept of hypnotic hallucination has a crucially different ontological nature depending on the theoretical view, these previous studies (Mazzoni et al., 2009; McGeown et al., 2012) do not contribute to the question concerning automaticity. They were designed to measure only imaginative abilities in and out of hypnosis. In contrast, the purpose of this study was to test the nature of hypnotic responding by especially focusing on the question of automaticity as well as subjective experience. In the current study, especially in Experiments 2 and 3, we specifically aimed at tasks where mental imaginary cannot be used as a strategy. We also used only a few stringently tested, very highly responsive participants, because even highly suggestible persons may differ crucially from each other in the way they respond to the most difficult cognitive suggestions. This intensive case-study approach has been further supported by other researchers (see Woody & Sadler, 2005). This study consists of three different experiments where we tested the experience of color hallucinations with and without hypnotic induction. All the given suggestions in these experiments stated simply that a color change would occur without any instruction to actively add or drain color. Furthermore, an important feature of this study was that all experimental tasks were carried out while the participants were in their normal baseline state of consciousness, since both our highly hypnotizable experimental subjects (later referred to as TS-H and RM) were able to experience hypnotic suggestions posthypnotically. The participant TS-H is a model example of a somnabulic or virtuoso individual who is able to experience all the classic hypnotic phenomena that are scientifically documented (Hilgard, 1965). TS-H participated in every experiment in the present study and participant RM in Experiments 1 and 3. According to the current praxis of research, these two individuals should, even with the most stringent criteria, belong to the category of highly hypnotizable and therefore respond similarly to experimental tasks. Both of these individuals should also experience identical demand characteristics (Orne, 1969), expectations (Kirsch, 2001), and motivation to comply (Wagstaff, 1981). In Experiment 1, we studied color alterations with and without hypnosis using the same Mondrian image stimuli as in previously mentioned studies (Kosslyn et al., 2000; Mazzoni et al., 2009; McGeown et al., 2012) with the addition that we also collected reports about the qualitative aspects of the subjective experiences. It turned out that the use of hypnosis was necessary for experiencing color changes in the Mondrian figure itself (not only in mental images) even for the model example of a very highly hypnotizable person, TS-H. Therefore Experiments 2 and 3 focused on the nature of hypnotically induced alterations with a more rigorous methodology, including collection of objective response time data along with the subjective reports. TS- H responded to real colors and suggested colors in briefly presented

4 264 SAKARI KALLIO AND MIKA KOIVISTO displays with equal speed, implying that she experienced the color alterations spontaneously. METHOD The research was conducted according to the ethical standards of the American Psychological Association (APA) and approved by the Ethics Committee of the University of Turku, Finland (statement 18/2011). All subjects gave their written informed consent for participation in the study. EXPERIMENT 1 In this experiment, we studied how a suggestion of color changes in a Mondrian-type image (see Figure 1) influenced the experience of two highly hypnotizable participants (TS-H and RM). The suggestion was given both during hypnosis (but experienced posthypnotically) and in normal waking state. The important difference in this study compared to previous studies (Mazzoni et al., 2009; McGeown et al., 2012) was that the participants were not asked to do anything actively (e.g., add color or drain color), but instead the suggestion stated that the changes would just happen when the person looked at the image. Participants Two very highly hypnotizable participants were included in the first experiment. The first participant (TS-H) was a 45-year-old right-handed female office worker who is an experienced subject in hypnosis experiments (e.g., Fingelkurts, Fingelkurts, Kallio, & Revonsuo, 2007a, 2007b; Kallio, Hyönä, Revonsuo, Sikka, & Nummenmaa, 2011). She has no history of neurological or mental illnesses and her psychometric profile is normal (Kallio et al., 2011). TS-H scores at the top of the most widely used hypnotic susceptibility scales, the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A; Shor & Orne, 1962) and the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C; Weitzenhoffer & Hilgard, 1962) and experiences very vivid visual and acoustic hallucinations. She experiences spontaneous posthypnotic amnesia and is typically entirely unaware of the suggestions that she has been given during the hypnotic state. She can also be hypnotized by using a posthypnotic one-word suggestion so that the process of hypnotizing her and giving suggestions takes only a very short time (for a video clip of the hypnotizing process, see Kallio et al., 2011). There is a body of research that shows changes in her brain functioning when hypnotized (e.g., Fingelkurts et al., 2007a, 2007b; Kallio, Revonsuo, Lauerma,

5 SEEING BLUE AS RED 265 Hämäläinen, & Lang, 1999). TS-H s automatic eye movements and pupil size also change during hypnosis (Kallio et al., 2011), giving further support to the thesis that she is subject to changes in brain functioning during hypnosis. The other participant (RM) was a highly hypnotizable 40-year-old right-handed female. On the two most widely used scales measuring hypnotic susceptibility (HGSHS:A, Shor & Orne, 1962; and SHSS:C, Weitzenhoffer & Hilgard, 1962), RM scored 12/12 and 9/12 points, respectively. RM also responded positively to most of the more demanding items measuring cognitive changes associated with hypnosis (e.g., amnesia, auditory hallucination, and posthypnotic behavioral responses). Like TS-H, she also responds to one-word hypnotic inductions, and hypnosis can therefore be induced and cancelled identically between RM and TS-H. Importantly, RM does not respond to an item measuring the experience of a negative visual hallucination, that is, a suggestion of failing to see an object placed in front of the person. Stimuli We presented, in turn, two figures (each 13 cm x 8.5 cm) resembling the art by Dutch painter Piet Mondrian. One of the stimuli was in full color and the other was a gray-scale version of the same image (Figure 1). The same stimuli have previously been used when demonstrating the functional specialization of the visual cortex (Zeki et al., 1991) and thereafter in several experiments testing the changes in color perception in association with hypnosis and hallucinations/mental imagery (Kosslyn et al., 2000; Mazzoni et al., 2009; McGeown et al., 2012). The Procedure with Hypnosis First, the ability to add color to the gray-scale version was tested with hypnosis. In the beginning, the participants were allowed to familiarize themselves with the figures by just presenting them briefly. After hypnotic induction (a one-word induction, see Kallio et al., 2011, was used in all experiments with both TS-H and RM), the following suggestion was given: Soon you will be shown a gray-scale image again and after a couple of seconds you will notice that different colors will start to appear in it. After a while, the colors will become bright and clear and you will easily see the pattern as a full-color image. After this suggestion, hypnosis was cancelled and the gray-scale image was shown. The participants had 30 s to look at it and then were asked to report what they see in the image. The same procedure was repeated with the color version of the Mondrian figure with the exception that

6 266 SAKARI KALLIO AND MIKA KOIVISTO the suggestion stated that the colors will start to fade until the image is entirely in gray scale. Results TS-H reported that the gray-scale image turned from a gray-scale to a full-color image (which she found very surprising). She was further asked to point out which colors she saw in each part of the pattern and to rate the strength of the colors. She described the color of each square of the pattern. On a 1- to 5-point scale (1 indicated no color and 5 indicated full colors), she rated the color strength in each square to be between 4 and 5. After this, she was shown the full-color Mondrian image and was asked to compare the two images. She described the colors in the gray-scale image (the altered colors) as different and normal colors like pure red and pure blue. Her subjective experience was a similar surprise when it was suggested that colors would fade and disappear from the colored image. This time she reported that the colors started to fade until there were only shades of gray. She rated the color strength as being 1. Participant RM reported that she could not detect any change in the Mondrian figure either when the gray-scale or color version was shown. When shown the color figure, she rated the color strength as 5 and between 1 and 2 when she was shown the gray-scale image. The Procedure Without Hypnosis Following the procedure used in a previous study (Mazzoni et al., 2009), the participants were first given the instruction: Previous research has shown that some people with very high levels of imaginative ability are able to see a color stimulus as gray and a gray stimulus as colored. Research has also shown that people can respond to suggestions for perceptual alterations whether or not they have been hypnotized. The purpose of this test is to assess your ability without hypnosis. Then exactly the same suggestions that were used with hypnosis were repeated without hypnosis. Results TS-H reported that she was not able to notice anything changing in the images during the 30-second period she was given to look at them. She reported that she could imagine colors in her mind s eye but she could not see any real change in the image itself and reported the color strength as being 5 for the colored image and 1 for the gray-scale image. RM reported that she could think the colors as somewhat different but

7 SEEING BLUE AS RED 267 was not able to see any change. She reported the color strength as 5 in the colored image and between 1 and 2 in the gray-scale image. Discussion The subjective reports in Experiment 1 suggest that even highly hypnotizable individuals may not experience real perceptual color alterations in the Mondrian stimulus without hypnosis. The use of hypnosis was necessary but not sufficient for such alterations (RM did not experience them with hypnosis). TS-H seemed to experience the alterations after the posthypnotic suggestion in a seemingly spontaneous and automatic manner without any effort. Therefore, we examined the nature of posthypnotically induced color alterations in TS-H more closely by using a demanding perceptual task with measures of response speed. The condition in which a suggestion is given without hypnosis was not applied in the further experiments as the results of the present experiment implied that TS-H does not experience color alterations without hypnosis. EXPERIMENT 2 We applied a posthypnotic suggestion of color change targeted to affect only specific objects in briefly displayed stimulus arrays. The experimental task was designed to be such that the suggested kind of alteration in conscious color experience should not be possible (for TS- H herself or for control participants) when using ordinary top-down processes in goal-directed mental imagery. The participants were asked to report the number of red items in each array as fast and accurately as possible (see Figure 2a). In the posthypnotic condition, a color alteration suggestion was targeted to specific items ( all squares are red, see Figure 2b). The control participants performed in a simulation condition and tried to mimic the performance of an observer who sees the squares as red. If TS-H experiences the suggested color alterations spontaneously, it should be an easy task for her to count the number of red items and to press the corresponding color. The responses of the control participants in the simulation condition should be considerably slower than their responses to real colors, because they have to count the number of red items and add to this sum the number of nonred squares. Participants In addition to TS-H, 2 healthy women (ages 40 and 51) and a 47-year old man (C1-C3) participated as control participants.

8 268 SAKARI KALLIO AND MIKA KOIVISTO Figure 2. (a) Examples of the stimuli in Experiments 2 3 in the normal condition and (b) in the posthypnotic/simulation condition Each display was presented for 500 ms and the participants task was to report the number of red items. If the posthypnotic suggestion squares are red is effective, the display on the right side should look like the display on the left side and the participant should report seeing two red items without any need for additional cognitive operations or calculations. In order to simulate the effect, one needs to add up all the red items and the blue squares and to press the answer button accordingly. Stimuli Each stimulus display consisted of 12 items (1.1 x 1.1 ) in a 3 x 4 array (5.1 x 6.9 ). In the normal condition (NC), the arrays contained three to four circles, three to four triangles, three to four plus symbols, and zero to two squares in random positions. In each display, either zero, one, two, or three of the items were red and the other items were blue (the squares were always red). The luminance was 5.2 cd/m2 for the red and blue colors and 51 cd/m2 for the white background (see Figure 2a). The stimulus displays in the posthypnotic condition (PHC) and simulation condition were otherwise identical to those in NC, but the color of the squares was always blue (see Figure 2b). Each display contained either zero red items and zero squares, zero red items and one blue square, one red item and one blue square, or one red item and two blue squares, while the other items were blue. TS-H performed following the posthypnotic suggestion that all squares were red, whereas the control participants were asked to perform as if they were under such posthypnotic suggestion (simulation condition). Therefore, under the PHC or simulation, the number of red targets was also zero, one, two, or three. Procedure The stimuli were presented on a 19 CRT monitor from a distance of 150 cm with E-prime software (E-Prime 2.0, Psychology Software Tools). Each trial began with the appearance of the fixation point on the screen

9 SEEING BLUE AS RED 269 for 700 ms, followed by a stimulus display for 500 ms. The participants performed 11 experimental stimulus blocks (40 trials/block). Eight of the blocks involved the PHC/simulation and three NCs. The blocks in the NC were performed as the first, sixth, and eleventh blocks (in the beginning, middle, and end of the session). The first experimental blocks in each condition were preceded by a practice block of 40 trials. In the normal condition (NC), the task was to report the number of red items after each array by pressing one of four response buttons on the top of the pad (Dual Action; Logitech) with the thumb of the right hand. The alternatives were (a) I saw 0 red items, (b) I saw 1 red item, (c) I saw 2 red items, or (d) I saw 3 red items. The participants were asked to respond as quickly and accurately as possible. Prior to the posthypnotic condition, TS-H was given the following suggestion in hypnosis: Soon you will see different kinds of objects on the screen and all squares will be of red color. You will see only red squares on the screen. There can, however, be other objects as well which can appear in either red or blue color, however, all squares that you see are always red. After this, hypnosis was cancelled and the same task instructions as in the NC were given. Thus, TS-H performed the PHC in a normal state of mind (but note that the suggestion of color change was given in hypnosis). A central reason for adopting this procedure was that, when given the one-word hypnotic induction, TS-H immediately becomes motionless, responds slowly and major changes in her eye movement behavior take place (Kallio et al., 2011, see also a video clip). Her reaction times would thus be heavily confounded by her response to a mere hypnotic induction. In the simulation condition, the control group was given instructions to try to imitate a person who sees all squares as red, that is, to respond as if they would see all squares as red. They were informed that they were allowed to use any strategies that they thought would help them to perform the task efficiently. Data Analysis A univariate analysis of variance (ANOVA) with Condition (2: NC vs PHC/Simulation) and Number of Targets (4: 0, 1, 2, 3) as fixed variables, and reaction time (RT) in each individual trial as the dependent variable was performed for each participant s data. Only trials with correct responses were included. In NC, a correct response corresponded to the number of red items. In the PHC and simulation, a correct response matched the sum of chromatically red items and blue squares. Accuracy was analyzed with the nonparametric chi-square test.

10 270 SAKARI KALLIO AND MIKA KOIVISTO Results and Discussion For TS-H s RTs (see Figure 3a), the only significant finding was the main effect for Target, F(3, 394) = 6.14, p <.001, η p 2 =.045, which showed that her RTs to one-target trials were the fastest. Most importantly, Condition did not have any main effect (F < 1) or interaction with the number of targets (F < 1). These results show that TS-H responded with equal speed to the targets when they were suggested to be red as compared with the situation when they really were red. The control participants RTs (see Figure 3b) were significantly faster in the NC than in the simulation, C1: F(1, 380) = , p <.001, η p 2 =.591; C2: F(1, 397) = 494,20, p <.001, η p 2 =.555; C3: F(1, 425) = 574,85, p <.001, η p 2 =.575. C1 also showed a significant effect for Target, F(3,380) = 4.94, p =.002, η p 2 =.03, which was due to fastest RTs in response to three-target trials (most probably reflecting a speedaccuracy trade-off, as the three-target trials were associated with the largest number of errors). C2 and C3 showed Target x Condition interactions, F(1, 397) = 5.20, p =.002, η p 2 =.038 and F(3, 425) = 7.26, p <.001, η p 2 =.049, which were due to the slowest RTs in the two-target trials in the simulation. TS-H s accuracy (see Table 1) was higher in the PHC than in the NC for the two-target trials. Accuracy was higher for three-target items in the NC than in the PHC for TS-H and in the simulation for the controls C1 and C2. TS-H s overall RTs were rather long. However, in spite of her slowness, especially in the early stimulus blocks, her speed increased (apparently due to a general practice effect) and, in the last stimulus blocks of the experiment, she was significantly faster in the PHC than the control participants in simulation (see Figure 4a and b). In summary, under the posthypnotic suggestion squares are red, TS-H reported seeing the blue squares as red. Moreover, her response speed in the PHC was equal to her speed in the NC. These results suggest that the posthypnotic suggestion induced an alteration in TS-H s color perception and that the objects appeared in their altered color spontaneously when they entered visual awareness. In contrast, the control participants who simulated the effects of the suggestion categorized the blue squares as red considerably slower than the real red colors, taking almost twice the time that was needed in responding to the real color. EXPERIMENTS 3A AND 3B In order to further confirm that TS-H s lack of response time difference between responses to posthypnotically induced colors and real colors reflects genuine perceptual color alterations, she served as her

11 SEEING BLUE AS RED 271 Figure 3. Response times in the normal condition (NC), the posthypnotic condition (PHC), and simulation as a function of the number of target items in Experiment 2: (a) In PHC, Participant TS-H performed under the influence of a posthypnotic suggestion, (b) whereas the control participants only simulated the influence of such suggestion. The error bars indicate the standard error of the mean.

12 272 SAKARI KALLIO AND MIKA KOIVISTO Table 1 Proportion of Correct Responses in Experiments 2 3 as a Function of Test Condition and Number of Targets Condition Normal (NC) Posthypnotic (PHC) Simulation Subject Targets Targets Targets Exp 2 TS-H C C C Exp 3A TS-H RM C C C Exp 3B TS-H RM Note. Bolded, italicized scores differ statistically significantly (p <.05) from the corresponding score in the normal condition. The underlined scores in Experiment 3B are significantly higher than the corresponding simulation scores in Experiment 3A.

13 SEEING BLUE AS RED 273 Figure 4. (a) Response times as a function of stimulus block in Experiment 2. The response times of TS-H and the control participants decreased as the experiment proceeded, particularly in the posthypnotic condition (PHC), F(7, ) = 12.76, p <.001, ηp 2 =.795. Although the RTs of TS-H were generally slower than those of the controls in the beginning of the task, they were faster than those of the control participants in the PHC at the end of the task, Block x Participant: F(3, 148) = 3.55, p =.016, ηp 2 =.067. (b) Response times in the last PHC block and the last normal condition (NC) block of Experiment 2. TS-H s response speed did not differ between the PHC and the NC in the last blocks of the experiment. Although her speed was slower than that of the control participants in the NC, under the influence of posthypnotic suggestion, she was faster than the controls who were simulating the effects of the suggestion in the PHC, Condition x Participant: F(1, 308) = 71.68, p <.001, ηp 2 =.189. Thus, in spite of the general slowness of TS-H, posthypnotic suggestion facilitated her performance to such a degree that she was faster than the simulators by the end of the experiment.

14 274 SAKARI KALLIO AND MIKA KOIVISTO own control and tried to simulate the influence of the posthypnotic suggestion in a normal state of consciousness (Experiment 3A). She performed the same task under the influence of a real posthypnotic suggestion (Experiment 3B). We also tested RM in order to study how the posthypnotic suggestion to experience color changes affected her performance, even though she did not report experiencing such a change in Experiment 1. Participants In Experiment 3A, TS-H, RM (see Experiment 1), and 3 healthy control participants (C4-C6) with normal or corrected-to-normal vision (45-year old male and 37- and 46-year-old females) were tested. In Experiment 3B, the two highly hypnotizable subjects (TS-H and RM) participated. Stimuli and Procedure Visual stimulation and the stimulus arrays were identical to those in Experiment 2, with the exception that the red and blue colors were reversed so that each display contained zero to three blue target items while the other items were red. The task was to report the number of blue items as quickly and accurately as possible. In Experiment 3A, all participants simulated performance as if they would have been given a posthypnotic suggestion to see the squares as blue. Four stimulus blocks were performed: An NC block was performed first, followed by two simulation blocks and finally by an NC block. A practice block preceded the first experimental blocks in both conditions. In addition, in Experiment 3B the procedure of Experiment 3A was repeated for TS-H and RM with a posthypnotic suggestion stating that the squares were blue. Results and Discussion Experiment 3A. When TS-H simulated posthypnotic performance, her RTs were significantly longer than those in response to the real color (see Figure 5a), F(1, 112) = , p <.001, η p 2 =.874. Note that she lacks the data point in the three-target condition of the simulation because she scored all the trials incorrectly in this condition. Similarly, the RTs of RM, F(1, 149) = , p <.001, η p 2 =.545 (see Figure 5b), and the control participants (see Figure 5c) were longer in simulation than in the NC, C4: F(1, 128) = , p <.001, η p 2 = 982; C5: F(1, 128) = , p <.001, η p 2 =.519; C6: F(1, 131) = , p <.001, η p 2 =.641. Thus, without the posthypnotic suggestion, TS-H and RM showed the same effect as the control participants: RTs were substantially longer when simulating the effects of the posthypnotic suggestion than when responding to the real color of the stimuli.

15 SEEING BLUE AS RED 275 Figure 5. (a) Response times of TS-H, (b) RM, and (c) control participants in the normal condition (NC) and the simulation condition as a function of the number of target items in Experiment 3a. Note that TS-H lacks the three-target data point in the simulation because she performed all the three-target items incorrectly without the aid of the posthypnotic suggestion. In Experiment 3B (dotted lines), TS-H and RM performed either in the NC or under the influence of a posthypnotic suggestion (PHC). The error bars indicate the standard error of the mean. TS-H s accuracy of responding (see Table 1) was significantly lower in the simulation than in the NC for one-, two-, and three-target trials. All control participants showed lower performance in the simulation than in the NC for three-target trials, and C4 showed this effect also for two-target trials. Experiment 3B. Here TS-H and RM performed under the influence of a posthypnotic suggestion (PHC). In contrast to the results of Experiment 3A, TS-H s accuracy did not differ significantly between the NC and the PHC in any of the target conditions (ps.091) (see Table 1). In addition, the response times did not differ between the NC and the PHC, F(1, 141) = 0.15, p =.698, η p 2 =.997 (see Figure 4a and 4b). Comparison of TS-H s RTs between Experiments 3A and 3B confirmed that the RT difference between the NC and the PHC was greater when she simulated posthypnotic performance than when she was really under the influence of the suggestion, F(1, 253) = , p <.001, η p 2 =.572. TS-H s accuracy was higher in PHC than in simulation for one-target trials, x2(1, n = 40) = 10.00, p =.003, two-target trials, x2(1, n = 40) = 6.14, p =.013, and three-target trials, x2(1, n = 40) = 21.54, p <.001.

16 276 SAKARI KALLIO AND MIKA KOIVISTO RM did not report color alterations but classified the target items in 1- to 3-target conditions according to their real color. In 38% of the PHC trials, she was not able to respond within the time that the computer allowed for responding (3300 ms). Therefore, the analysis of her RT data included both correct and incorrect responses given within 3300 ms after stimulus onset. Her responses were significantly longer in the PHC than in the NC, F(1,162) = 38.66, p <.001, η p 2 =.193. In summary, TS-H could not simulate the effects of the posthypnotic suggestion in her own performance. The posthypnotic suggestion, however, improved response times and accuracy as compared with performance in the simulation condition and eliminated the differences in responding to suggested colors and real colors. Consistent with the results of Experiments 1, RM did not report color changes, but her RTs were slowed down by the suggestion. Her bodily restlessness during PHC suggested that she had to concentrate very hard in order to overcome unintentional distracting influences of the suggestion. When interviewed afterwards, she reported that My eyes say that some of the items are red while my brain says that they are blue this strange feeling makes it really hard to give a response. When interviewed afterwards, neither TS-H nor RM remembered the posthypnotic suggestion due to suggested posthypnotic amnesia. DISCUSSION Previous research has suggested that some people with very high levels of hypnotic susceptibility may be able to see a color stimulus as gray and a gray stimulus as colored (Kosslyn et al., 2000; Mazzoni et al., 2009; McGeown et al., 2012). In Experiment 1, neither of the two highly hypnotizable participants seemed to be able to experience the suggested color changes in the Mondrian figure without hypnosis, suggesting that, in the normal state of consciousness, one cannot overcome the automatic process of color perception but sees the colors according to their wavelength. Both highly hypnotizable participants stated clearly that they could imagine the figure in altered colors in their mind s eye but they could not really see such changes in the figure, raising the possibility that imagery and seeing has been confounded in the previous studies (Mazzoni et al., 2009; McGeown et al., 2012) reporting alterations without hypnosis. After posthypnotic suggestion, however, TS-H spontaneously reported seeing vivid changes in the Mondrian figure while RM reported no changes in the image. In addition, in the tasks measuring response times (Experiments 2 3), TS-H reported the number of items with the suggested color with equal speed to the number of items

17 SEEING BLUE AS RED 277 with real colors. This pattern, and the fact that none of the participants (including TS-H herself) could simulate it, suggests that, if the altered colors are really seen, they appear in visual awareness spontaneously without the need to use effort-demanding imagery or intentional top-down strategies. The spontaneous nature of TS-H s perceptual experiences is highlighted by the fact that, in posthypnotic conditions, no task instructions for trying to alter the color was given in any of the experiments. Interestingly, the response pattern of RM in the posthypnotic condition of Experiment 3b was quite different. The posthypnotic color suggestion dramatically affected her performance, rendering her response times very slow and causing a subjective experience of incongruity between what she saw and what she felt. Although RM did not experience color alterations, it is clear that her altered experiences were involuntary and not generated by trying to use visual imagery. Perception of real colors in the normal conditions of Experiments 2 3 did not depend on the number of target items. This pattern is consistent with the view that colors pop out automatically (Treisman & Gormican, 1988) and that small numbers (one to fouor items) can be enumerated preattentively by using a parallel process called subitizing (Dehaene & Changeux, 1993). On the other hand, the posthypnotic color alteration suggestions were targeted to specific shapes (e.g., all squares are red ). Therefore, performance in the posthypnotic and simulation conditions required recognition of these shapes. In the simulation conditions, reaction times slowed in the two-target trials and errors increased in the three-target trials, suggesting that the target shapes could not be recognized with preattentive parallel processing. This explains why TS-H failed to report color alteration for some of the items in the posthypnotic three-target trials: A prerequisite for selective color alteration is that the relevant shapes are recognized with serial attention. The subjective descriptions of TS-H are consistent with this view. She reported that she could not always see all red (or blue) targets directly but noticed some of them a bit later. These notions imply that the altered colors did not pop out preattentively like real colors do (Treisman & Gormican, 1988) but required that the relevant shapes were within the scope of attention. TS-H s relatively slow reaction times to the number of colors in the normal conditions of Experiments 2 3 require explanation. We can come up with three possible explanations. One would be that that TS-H has exceptionally slow reaction times in general. However, a previous study (Kirjanen, 2013) showed that, in a simple-choice reaction-time task, TS-H s reaction times were in the midnormal range when compared to four normal controls. The second explanation states that she intentionally or unintentionally gives the impression that she sees

18 278 SAKARI KALLIO AND MIKA KOIVISTO altered colors although she does not. This could be done by the slowing down of responding in the normal condition so that the speed would match that in the posthypnotic condition. This explanation for the entire pattern of results does not seem plausible, because it has to attribute exceptional cognitive abilities to TS-H. It would require constant monitoring of response speed and accuracy throughout Experiments 2 3 while performing the tasks. Also, it requires the ability to gradually speed up the reaction times in order to bring forth results that resemble a normal learning curve throughout the sessions in different conditions and experiments. It must be noted that neither TS- H nor RM ever received (nor asked for) any feedback on any aspects of their responding in any of the experiments. Since TS-H never received any feedback, she would have to remember her strategy and response speed across the series of experiments in order to be able to somehow adjust her performance between the normal and posthypnotic conditions but also across the experimental tasks and sessions that were performed during a period of 18 months. A third explanation is implied when comparing the learning curve for RTs in the PHC and NC tasks (see Figure 4a). The striking similarity of these curves suggests that both the PHC and NC tasks were performed by using an identical strategy. Since TS-H reported that she noticed some of the red items a bit later than the other ones in the PHC condition (possibly because shape recognition failed for suggestion-relevant items located far away from the focus of attention), the logical consequence is to start to pay closer attention to all items in each pattern, that is, to use a serial search strategy. The important difference between TS-H and the simulators was that TS- H never had any idea about when to rely on pop-out effect and when to use the serial search strategy. Due to posthypnotic amnesia, the PHC and NC conditions became an identical task for TS-H. In contrast, the control group had clear knowledge of what strategy to use before each condition. Thus, the explanation that TS-H truly sees the colors as suggested is more viable than the general slowness of responding or use of any intentional or unintentional cheating strategy. The findings from Experiments 1 3 have three important conclusions and implications. First, the results support the interpretation that TS-H subjectively experienced the targets according to the posthypnotically suggested color and not according to their true wavelength. This happened spontaneously, without effort-demanding and purposeful imagery in response to the static Mondrian figure and in response to specific shapes in a briefly presented display. Second, the behavioral outcomes and subjective experiences of the two highly hypnotizable individuals (TS-H and RM) differed remarkably in response to posthypnotic suggestions. This provides more evidence that the concept of highly hypnotizable may not be rigorous enough for forming

19 SEEING BLUE AS RED 279 groups in hypnosis studies, as these individuals do not constitute a homogenous group (see, e.g., McConkey, Glisky, & Kihlstrom, 1989) and further supports the argument that case studies are a feasible approach especially when studying the rarest hypnotic phenomena (e.g., Kallio & Revonsuo, 2003, 2005). Third, our measurements of objective response times and accuracy data are clear methodological advantages in relation to previous studies (Kosslyn et al., 2000; Mazzoni et al., 2009; McGeown et al., 2012), which have taken the subjective reports of participants at face value as indicators of color alterations. Also, the examination of the qualitative aspects of color alterations in Experiment 1 helped us to clarify that, while color changes can be experienced in imagery without hypnosis, the use of hypnosis is necessary but not sufficient for alterations of color perception. Our findings do not exclude the option that some highly select individuals (see Mazzoni et al., 2009) may be able to modify the activity of their color-processing brain areas with effortful imagery without hypnosis. However, this kind of goal-directed mental imagery should not be mixed with automatic hallucinations. How is it in theory then possible that suggestions alter color perception? In addition to the current results, there is also previous research that suggests (see DePascalis, 1994, 1999; Kallio & Koivisto, 2013; Koivisto, Kirjanen, Revonsuo, & Kallio, 2013; see also Spiegel, Cutcomb, Ren, & Pribram, 1985) that hypnosis may give rise to a preconscious mechanism, which then automatically matches the visual input to a given hypnotic suggestion. Next, we show how this evidence can be connected with the current models of visual consciousness research. A visual stimulus elicits a feedforward flow of information in the ventral stream from primary visual cortex toward inferior temporal cortex. In recent theories of visual awareness (e.g., Di Lollo, Enns, & Rensink, 2000; Hochstein & Ahissar, 2002; Lamme, 2010), the feedforward activation of higher visual areas is not sufficient for full conscious perception. The theories instead propose that the contents of conscious perception are ultimately generated by a further recurrent phase of processing in which higher brain areas interact with early visual areas via feedback connections. Most relevant to the present study, binding of color and shape into coherent conscious perception depends on recurrent interactions between higher and early cortical visual areas (Bouvier & Treisman, 2010; Koivisto & Silvanto, 2012; Lamme, 2010). In addition to the recurrent or feedback interactions between visual areas in the ventral stream, a second type of feedback in visual processing takes place. The visual input is also projected rapidly from the early visual areas to the prefrontal cortex via the dorsal stream. This process results in a coarse shape representation activating expectations about the input image, which are then back-projected to the temporal cortex (Bar, 2003). On the basis of this general framework (see Figure 6), it can be proposed

20 280 SAKARI KALLIO AND MIKA KOIVISTO Figure 6. A schematic model for a posthypnotically induced alteration of color perception (modified after Bar, 2003; Tapia & Breitmeyer, 2011). A visual stimulus initiates a fast but coarse shape-recognition process by projecting the low-spatial frequency content of visual input via magnocellular-dominated channels to the visual areas in the dorsal stream and prefrontal cortex. The fast shape recognition process in dorsal and prefrontal areas activates the association between the shape and the posthypnotically suggested color and modulates in a top-down manner the activity in the slower, parvocellular-dominated ventral stream. High-resolution object representations and conscious perception (including the altered color) arise as a consequence of reentrant processing between higher and lower visual areas. that color alterations can occur if the suggestions modulate the recurrent interactions, which generate the contents for the final conscious perception. In the case of shape-specific alterations, the perceptual system must first identify the relevant shape by comparing the perceptual input to the features specified in the suggestion. Once a match is found, the influence of the suggestion on color processing can be triggered. This can be realized for example as a top-down modulation from parietal or prefrontal cortex to the ventral brain areas (Bar, 2003; Bouvier & Treisman, 2010; Koivisto & Silvanto, 2012; Lamme, 2010). The experiences of the highly hypnotizable RM, who did not report color alterations but described a conflict between what she sees and feels, can be explained by assuming that the influence of hypnosis did not extend to the end of the processing chain. Either the effect of the suggestion on neural processing was too weak to have a complete influence, or she consciously perceived the real color before the suggestion

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