An Investigation of the Effects of Opioid Receptor Blockade on Changes in Self-esteem and Attentional Bias Toward Social Cues
Phase: NA
Conditions: Self Esteem
Sponsor: McGill University

 
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Study Protocol with SAP 
 
Official Title: An Investigation of the Effects of Opioid Receptor Blockade on Changes in Self-
esteem and Attentional Bias Toward Social Cues 
 
ClinicalTrials.gov ID: A02-B12-11B 
 
Date: February 11, 2021 
 
 

 
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Background 
Given the evolutionary importance of social ties for survival, humans are thought to have 
evolved psychobiological mechanisms to monitor and safeguard the status of their social bonds. 
At the psychological level, self-esteem is proposed to function as a gauge—sociometer— 
reflecting one’s social belongingness status (Leary & Baumeister, 2000). Thus, negative self-
referential cognitions (e.g., “I am worthless”) and their accompanying negative feelings signal 
failure to maintain an adaptive level of closeness to other people. In support of Sociometer 
Theory, it is well established that events threatening one’s sense of social connection, or social 
value in the eyes of others, evoke decrements in self-esteem, both in the laboratory (Gruenewald, 
Kemeny, Aziz, & Fahey, 2004; Leary et al., 2003; Leary, Haupt, Strausser, & Choket, 1998; 
Leary, Tambor, Terdal, & Downs, 1995) and daily life (Denissen, Penke, Schmitt, & van Aken, 
2008; Harris & Orth, 2019); further, there is a direct correlation between feelings of inclusion 
and in-the-moment self-esteem (Leary et al., 1995). 
 At the biological level, the endogenous opioid system, which plays a key role in 
mediating pain and pleasure (Fields, 2007; Leknes & Tracey, 2008), appear to be an important 
substrate for the hedonic signalling needed to regulate social behaviour. According to the Brain 
Opioid Theory of Social Attachment (Herman & Panksepp, 1978; Machin & Dunbar, 2011; 
Panksepp, 1998), endogenous opioids (specifically, μ-opioids) contribute to feelings of reward, 
safety, and warmth experienced in the presence of supportive others, thus positively reinforcing 
the social bond, whereas declines in opioidergic activity precipitated by loss of social contact 
evoke feelings of separation distress, and drive consequent attempts to regain closeness. 
Therefore, opioidergic activity is suggested to underpin the workings of an “emotional 
barometer” monitoring the availability of social support (Panksepp, 1998). In support of this 

 
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idea, research has shown that administration of opioid receptor antagonists such as naltrexone 
reduces feelings of social connection induced by the presentation of affiliative stimuli, such as 
warm written messages from participants’ close others (e.g., friends, family, and romantic 
partners) (Inagaki, Hazlett, & Andreescu, 2019; Inagaki, Ray, Irwin, Way, & Eisenberger, 2016), 
and increase feelings of disconnection in daily life (Inagaki et al., 2016). 
Noting the parallels between Sociometer Theory (Leary & Baumeister, 2000) and the 
Brain Opioid Theory of Social Attachment (Panksepp, 1998), we investigated whether 
endogenous opioids may serve as the biological correlate of the sociometer. Specifically, we 
hypothesized that opioid receptor blockade with the drug naltrexone would produce a state that is 
analogous to the experience of social disconnection. Just as opioid receptor blockade potentiates 
separation distress in non-human animals, we reasoned that it may similarly promote reductions 
in self-esteem, considered to be a cognitive derivative of separation distress in humans (Watt & 
Panksepp, 2009). 
In addition to investigating the effects of opioid receptor blockade on self-esteem, we 
also took this opportunity to examine a possible behavioural consequence of opioid receptor 
blockade. The Brain Opioid Theory of Social Attachment argues that a low endogenous opioid 
state heightens social need and motivates affiliative behaviour to restore well-being (Panksepp, 
1998), although there are boundary conditions for this effect. For example, non-human animal 
studies suggest that the effects of naltrexone on social motivation are often selective for more 
“safe” targets (e.g., increasing affiliation with Mom but not peers) (Martel et al., 1995). Notably, 
similar boundary conditions have been observed in work investigating the effects of acute 
psychological rejection on human social motivation; that is, social exclusion increases pursuit of 
social acceptance, but only from those individuals who appear to represent viable sources of 

 
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social connection (Maner, DeWall, Baumeister, & Schaller, 2007). This “cautious interest” 
makes sense considering that recently rejected people must balance their need for social 
connection against the risk of further rejection (Finkel & Baumeister, 2018). Thus, borrowing 
from DeWall et al. (Dewall, Maner, & Rouby, 2009), we focused on early-stage perceptual 
processes that are thought to maximize opportunities for social connection. Specifically, DeWall 
and colleagues showed that recently rejected (vs. control) participants oriented more quickly to 
faces signalling acceptance (in the form of a smile), but not disapproval. Similarly, we 
hypothesized that naltrexone (vs. placebo) would result in heightened social need manifested as 
increased attentional bias to smiling faces.  
To test these hypotheses, we administered naltrexone and placebo on two occasions, 
approximately one week apart, and then assessed self-esteem and attentional bias to accepting 
(vs. neutral and rejecting) faces. Given our focus on changes in self-esteem, we elected to use a 
within-subjects design because it allows us to control for individual differences in trait self-
esteem across drug conditions; moreover, a within-subjects design offers considerably greater 
statistical power, given the same number of participants, than does a between-subjects design.  
Study Objectives 
 
This study examined the effects of endogenous opioids on self-esteem and attentional 
bias toward social cues. This was accomplished by temporarily blocking endogenous opioid 
activity with the administration of an opioid receptor antagonist. 
Study Design and Methods 
 All research procedures were approved by the McGill University Medical Institutional 
Review Board (protocol #A02-B12-11B). The study used a randomized, within-subjects, 
placebo-controlled design in which participants received 50 mg oral naltrexone and matching 

 
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placebo on two occasions approximately one week apart (to provide a wash-out period for the 
drug); order of drug administration was counterbalanced and participants and experimenters 
were blind to drug condition (see “Drug/Placebo Information” below for details). After providing 
informed consent and confirming that they met the pre-conditions for the study (e.g., no alcohol 
within 24 hours, no drug use within 10 days, not pregnant), eligible participants were 
administered either naltrexone or placebo, by random assignment and in double-blind conditions, 
and were asked to wait for one hour before testing began; during this time they were allowed to 
perform quiet activities (e.g., reading).  
Approximately two hours after drug/placebo ingestion, we assessed self-esteem with the 
Rosenberg Self-Esteem Scale and attentional bias to accepting vs. rejecting faces with a Visual 
Probe Task. Participants remained in the lab for another hour so that side effects could be 
monitored. During the second testing session, participants were administered the alternate 
compound and then underwent identical procedures as described above.  
Participants/Eligibility Criteria 
Applicants were screened for normal health status. Exclusion criteria included: (1) allergy 
to naltrexone, (2) kidney or liver injury or disorder, (3) bipolar, panic, or psychotic disorders, (4) 
epilepsy, (5) smoking more than 15 cigarettes per day, (6) pregnancy, (7) substance abuse, (8) 
use of opioid analgesics, cocaine, recreational drugs (e.g., marijuana, LSD, ecstasy, etc.), or 
prescription medication (except oral contraceptives) within the past 10 days, (8) use of over-the-
counter drugs (e.g., analgesics, anti-inflammatories, sleeping aids, etc.) or alcohol within the past 
24 hours. Participants were also excluded if they reported that they were currently in pain (e.g., 
headache), or if they had used anti-diarrheal medications (e.g., Immodium, Kaopectate, Pepto-
Bismol) in the seven days prior to the study, as these substances may interact with naltrexone. 

 
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Because naltrexone is metabolized by the liver and kidneys, participants were required to provide 
medical records from within the past year reporting normal kidney and liver function results. If 
interested potential participants were not able to provide these records, we administered blood 
tests for kidney and liver function through an independent laboratory (Medisys, Montréal, QC); 
we compensated potential participants $15 for taking part in this process. Individuals with 
evidence of abnormal kidney or liver function were excluded from the study.  
All participants who passed initial kidney and liver screening were scheduled for 
participation in the experiment, and completed further screening on the two days of testing for 
drug use and pregnancy. Screening for drugs of abuse was conducted with a DrugCheck® Urine 
Drug Test - 5 panel (DTK, Barrie, ON). The test detects cocaine, opiates, δ9-
tetrahydrocannabinol, amphetamine, and methamphetamine. Urine pregnancy screening was 
conducted with the BFP hCG test strips (Fairhaven Health, Bellingham, WA, USA) in vitro test. 
There were no positive results on these tests and thus no participants were excluded at this stage. 
Thirty-five participants met the eligibility criteria and provided informed consent. 
However, seven participants were excluded from analyses because they did not complete all 
phases of the study (i.e., experienced side effects and/or did not return for the second testing 
session); moreover, self-esteem data was missing from two participants. Due to computer error, 
two participants were missing attentional bias data and two additional participants were excluded 
from attentional bias analyses because of outlying high error rates (Mogg, Bradley, De Bono, & Painter, 
1997). Thus, the final sample for self-esteem analyses consisted of 26 participants (11 men), aged 
18-45 years old (M=22.83; SD=5.53), and the final sample for the attentional bias analyses 
consisted of 24 participants (11 men, Mage=23.00, SDage=5.75, Rangeage=18-45). All participants 

 
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were fully debriefed at the conclusion of the study and compensated $100 (plus up to $40 for 
transportation and/or parking).  
Naltrexone and Placebo Information 
 
Participants were given 50mg of naltrexone hydrochloride (Revia, Bristol-Myers Squibb) 
or a matching placebo. Drug/placebo administration order was counterbalanced and participants 
and experimenters were both blind to drug condition. To ensure double-blind conditions, a 
compounding pharmacy (Paylan Pharmacy, Montréal, QC) prepared the naltrexone 
hydrochloride in an opaque blue, unmarked capsule packed with cellulose filler, and used 
identical capsules with the same cellulose filler as the placebo. An independent set of judges was 
unable to tell the capsules apart by inspection. 
Measures 
The Rosenberg Self-Esteem Scale  
The Rosenberg Self-Esteem Scale (Rosenberg, 1965) is a widely used 10-item self-report 
measure of global self-worth. Participants provide an assessment of both positive and negative 
feelings about the self by responding to items such as “On the whole, I am satisfied with 
myself,” and “I feel that I’m a person of worth, at least on an equal plane with others” on a 4-
point Likert scale ranging from “strongly agree” to “strongly disagree.” The scale was scored 
such that higher scores reflect higher levels of self-esteem. For exploratory purposes, we also 
calculated separate subscale scores for self-liking and self-competence as in (Tafarodi & Milne, 
2002). 
The Visual-Probe Task 
The Visual Probe Task (VPT; 39) is a visual cuing task widely used to assess attentional 
bias (Fox, Russo, Bowles, & Dutton, 2001; MacLeod, Mathews, & Tata, 1986). We used the 

 
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VPT as a measure of early-stage interpersonal attention (Dewall et al., 2009): specifically, 
attentional bias to social acceptance. Participants were seated in front of a PC laptop computer 
and instructed to stare at a fixation point (a black cross) on the screen. After 500 ms, two faces 
simultaneously appeared on the computer screen, separated by the fixation point. The stimuli 
consisted of smiling (accepting), neutral, or disapproving (rejecting) faces (see (Dandeneau et al., 
2007) for a complete description of the VPT). Specifically, two face stimuli, one neutral and one 
emotionally salient (i.e., accepting or rejecting) were presented on the computer screen, one on 
the left and the other on the right, for 500 ms; the faces were then replaced by a probe (either two 
dots aligned vertically [:] or two dots aligned horizontally [..]), which appeared on the side of 
either the neutral or accepting/rejecting face with equal probability. The probe remained on 
screen until participants identified its location by pressing the correct key on the keyboard (the 
letter q for the vertically aligned dots and the letter z for the horizontally aligned dots; both keys 
were labelled with the symbol of their corresponding probe). Participants were instructed to 
respond as quickly and accurately as possible in identifying the probe location; their response 
times (RTs) were recorded on each trial. The assumption is that, if participants’ attention is 
directed toward the emotional stimulus, then they should be faster to respond (i.e., will have 
smaller RTs) on trials in which the probe replaces the emotional stimulus versus trials where the 
probe replaces the neutral stimulus. Conversely, participants should be slower (i.e., will have 
larger RTs) when responding to a probe that replaces the stimulus they were not selectively 
attending to.  
The stimuli consisted of 64 pictures of 32 different individuals (50% females, 50% 
males), with 16 making neutral and accepting facial expressions and 16 making neutral and 
rejecting facial expressions (Dandeneau et al., 2007). Each neutral picture was matched with the 

 
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rejecting or accepting pose of the same person, thereby making 16 rejecting-neutral pairs and 16 
accepting-neutral pairs for the critical experimental trials. The task included two blocks, and 
each expressive-neutral pair was presented twice per block (once with the emotional face on the 
right and once on the left), making for a total of 64 neutral-accepting and 64-neutral-rejecting 
trials.  Of note, the version of the VPT we used (39) was preprogrammed to also include 64 
neutral-neutral trials for the testing of other research questions (these trials consisted of 8 neutral 
poses for each expressive-neutral pair). Although we did not have specific hypotheses for the 
neutral-neutral trials, we used these trials to assess the effects of naltrexone (vs. placebo) on 
reaction time in general. Thus, the entire task consisted of 16 practice trials, and 2 blocks of 96 
trials each for a total of 208 trials (16 practice, 64 neutral accepting, 64 neutral-rejecting, and 64 
neutral-neutral).   
Following (44), we discarded all inaccurate VPT trials (i.e., trials on which subjects did 
not press the key that corresponded to the probe location). Importantly, drug condition did not 
influence error rate (placebo=2.80% vs. naltrexone=2.69%). In addition, following (Dandeneau 
et al., 2007), we discarded individual trials on which participants responded faster than 200 ms or 
slower than two standard deviations above their overall mean RT. Attentional bias scores 
(acceptance bias scores and rejection bias scores) from both the naltrexone and placebo sessions 
were computed for each participant. Specifically, to obtain individual acceptance bias scores, we 
used RT data from trials on which an accepting-neutral stimulus pair was presented. Next, we 
subtracted each participant’s mean RT on “valid” trials (where the probe replaced the accepting 
face) from their mean RT on “invalid” trials (where the probe replaced the neutral face). 
Likewise, rejection bias scores were obtained by subtracting each participant’s mean RT on valid 
trials from their mean RT on invalid trials using data from the rejecting-neutral trials. In this 

 
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way, higher positive scores indicate greater attentional bias to the emotional (vs. neutral) face, 
and negative scores indicate disengagement from, or inhibition of attention to, the emotional 
face.  
Statistical Analyses 
To test our hypotheses, we conducted a series of repeated measures analyses of variance 
(ANOVA) with drug condition (naltrexone or placebo) as the within-subjects factor, and self-
esteem and VPT scores as the outcome measures; separate analyses were conducted for 
acceptance bias, rejection bias, and neutral-neutral trial RTs. To ensure that changes in the 
variables of interest were a function of the drug and not order of drug administration or the tasks 
participants completed prior to ours, we included order (naltrexone vs. placebo on Day 1), study 
participation (music pleasure vs. music cognition), and the interaction between these two 
variables as between-subjects factors in our statistical analyses. For full transparency, we also 
provide results without these control variables included in the model.  
Results 
Self-Esteem 
The repeated measures ANOVA revealed a significant effect of drug on self-esteem, F(1, 
22)=5.18, p=.033, η2 =0.19). As seen in Figure 1, mean self-esteem scores were lower on the 
naltrexone day (M=3.27, SE=0.07) compared to the placebo day (M=3.39, SE=0.09).1 There 
were no effects of drug administration order or prior study on self-esteem, nor were there any 
significant interactions between these variables and drug condition (all ps > .050). Of note, we 
also observed a significant drug order by prior study interaction, F(1, 22)=5.60, p=.027 on self-
 
1 When the order of drug administration and prior study variables were removed from analysis, the test statistics for 
the drug effect were as follows: F(1, 25)=6.45, p=.018, η2=0.20.  

 
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esteem; however, none of the contrasts were significant (all ps >.050), rendering this effect 
uninterpretable. 
As an exploratory analysis, we also examined the effect of naltrexone vs. placebo on the 
self-liking and self-competence subscales of our self-esteem measure separately (Tafarodi & 
Milne, 2002). Results showed that participants reported significantly lower self-liking on the 
naltrexone day, M=3.05, SE=0.10, relative to the placebo day, M=3.21, SE=0.11, F(1, 22)=6.54, 
p=.018, η2=0.23, whereas there was no effect of naltrexone on the self-competence subscale, F(1, 
22)=1.56, p=.225, η2=0.07.2 Results also showed the same drug order by prior study interaction 
that was observed for overall self-esteem on self-liking (F(1, 22)=8.72, p=.007), but not self-
competence (p > .050); other than this one interaction, there were no significant effects of drug 
administration order or prior study, nor were there any significant interactions between these 
variables and drug condition on either self-liking or self-competence component scales (all ps > 
.050) . 
Acceptance Bias 
The repeated measures ANOVA yielded a significant effect of drug on acceptance bias, 
F(1, 20)=4.42, p=.048, η2=0.18. As illustrated in Figure 2, acceptance bias scores were 
significantly higher following naltrexone (M=15.03, SE=7.23) vs. placebo (M=-6.52, SE=6.35), 
indicating that participants showed greater attention to accepting faces following naltrexone (vs. 
placebo) administration.3 There were no main or interaction effects of drug administration order 
or prior study on acceptance bias (all ps >.050).   
 
2 When the order of drug administration and prior study variables were removed from analysis, the test statistics for 
the drug effect were as follows: (1) self-liking: F(1, 25)=7.58, p=.011, η2=0.23; (2) self-competence: F(1, 25)=1.23, 
p=.278, η2=0.05. 
3 When the order of drug administration and prior study variables were removed from analysis, the test statistics for 
the drug effect were as follows: F(1, 23)=2.29, p=.143, η2=0.09.  

 
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Rejection Bias 
 In contrast to the findings for acceptance bias, there were no significant effects of drug on 
rejection bias scores, F(1, 20)=1.33, p=.262, η2=.06.4 In fact, the pattern of results was in the 
opposite direction from the acceptance bias score with nominally (but not significantly) less 
attention to rejecting faces following naltrexone (M = -6.02, SE = 4.32) vs. placebo (M = 1.35, 
SE = 5.12). There were no main or interaction effects of drug administration order or study on 
rejection bias (all ps >.050). 
Neutral-Neutral Trial RT 
The repeated measures ANOVA showed no significant effect of drug on neutral-neutral 
trial RTs, F(1, 20) = 0.34, p=.566, η2=0.02, although there was a significant drug by drug order 
effect, F (1, 20) = 11.84, p = 0.003: for participants who received naltrexone on Day 1, reaction 
times were greater in the naltrexone vs. placebo condition, Mdiff=35.90, F(1, 20)=12.69, p=.002, 
whereas there was no difference between drug condition for participants who received placebo 
on Day 1, Mdiff=-25.48, F(1, 20)=3.00, p=.099. Importantly, even though there may have been a 
slowing down of RTs in general (at least for those who received naltrexone on Day 1), this 
would not explain the primary effect of interest—i.e., faster RTs to accepting faces following 
naltrexone—in fact, this general slowing down would, if anything, work against this effect. 
  
 
 
 
 
4 When the order of drug administration and prior study variables were removed from analysis, the test statistics for 
the drug effect were as follows: F(1, 23)=0.80, p=.380, η2=0.03. 

 
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References 
Dandeneau, S. D., Baldwin, M. W., Baccus, J. R., Sakellaropoulo, M., & Pruessner, J. C. (2007). 
Cutting stress off at the pass: Reducing vigilance and responsiveness to social threat by 
manipulating attention. Journal of Personality and Social Psychology, 93(4), 651–666. 
http://doi.org/10.1037/0022-3514.93.4.651 
Denissen, J. J. A., Penke, L., Schmitt, D. P., & van Aken, M. A. G. (2008). Self-esteem reactions 
to social interactions: Evidence for sociometer mechanisms across days, people, and 
nations. Journal of Personality and Social Psychology, 95(1), 181–196. 
http://doi.org/10.1037/0022-3514.95.1.181 
Dewall, C. N., Maner, J. K., & Rouby, D. A. (2009). Social exclusion and early-stage 
interpersonal perception: Selective attention to signs of acceptance. Journal of Personality 
and Social Psychology, 96(4), 729–741. http://doi.org/10.1037/a0014634 
Fields, H. L. (2007). Understanding how opioids contribute to reward and analgesia. Regional 
Anesthesia and Pain Medicine, 32(3), 242–246. http://doi.org/10.1016/j.rapm.2007.01.001 
Finkel, E. J., & Baumeister, R. F. (2018). Attraction and Rejection 1 Attraction and Rejection. 
Fox, E., Russo, R., Bowles, R., & Dutton, K. (2001). Do threatening stimuli draw or hold visual 
attention in subclinical anxiety? Journal of Experimental Psychology: General, 130(4), 
681–700. http://doi.org/10.1037/0096-3445.130.4.681 
Gruenewald, T. L., Kemeny, M. E., Aziz, N., & Fahey, J. L. (2004). Acute threat to the social 
self: Shame, social self-esteem, and cortisol activity. Psychosomatic Medicine, 66(6), 915–
924. http://doi.org/10.1097/01.psy.0000143639.61693.ef 
Harris, M. A., & Orth, U. (2019). The link between self-esteem and social relationships: A meta-
analysis of longitudinal studies. Journal of Personality and Social Psychology. 

 
14
http://doi.org/10.1037/pspp0000265 
Herman, B. H., & Panksepp, J. (1978). Effects of morphine and naloxone on separation distress 
and approach attachment: Evidence for opiate mediation of social affect. Pharmacology 
Biochemistry and Behavior, 9(2), 213–220. http://doi.org/10.1016/0091-3057(78)90167-3 
Inagaki, T. K., Hazlett, L. I., & Andreescu, C. (2019). Opioids and social bonding: Effect of 
naltrexone on feelings of social connection and ventral striatum activity to close others. 
Journal of Experimental Psychology: General. http://doi.org/10.1037/xge0000674 
Inagaki, T. K., Ray, L. A., Irwin, M. R., Way, B. M., & Eisenberger, N. I. (2016). Opioids and 
social bonding: Naltrexone reduces feelings of social connection. Social Cognitive and 
Affective Neuroscience, 11(5), 728–735. http://doi.org/10.1093/scan/nsw006 
Leary, M. R., & Baumeister, R. F. (2000). The nature and function of self-esteem: Sociometer 
theory. In M. P. Zanna (Ed.), Advances in Experimental Social Psychology (pp. 1–62). San 
Diego: Academic Press. 
Leary, M. R., Gallagher, B., Fors, E., Buttermore, N., Baldwin, E., Kennedy, K., & Mills, A. 
(2003). The invalidity of disclaimers about the effects of social feedback on self-esteem. 
Personality & Social Psychology Bulletin, 29(5), 623–36. 
http://doi.org/10.1177/0146167203029005007 
Leary, M. R., Haupt, A. L., Strausser, K. S., & Choket, J. T. (1998). Calibrating the sociometer: 
The relationship between interpersonal appraisals and state self-esteem. Journal of 
Personality and Social Psychology, 74(5), 1290–1299. http://doi.org/10.1037/0022-
3514.74.5.1290 
Leary, M. R., Tambor, E. S., Terdal, S. K., & Downs, D. L. (1995). Self-esteem as an 
interpersonal monitor: The sociometer hypothesis. Journal of Personality and Social 

 
15
Psychology, 68(3), 518–530. http://doi.org/10.1037/0022-3514.68.3.518 
Leknes, S., & Tracey, I. (2008). A common neurobiology for pain and pleasure. Nature Reviews. 
Neuroscience, 9(4), 314–20. http://doi.org/10.1038/nrn2333 
Machin, A. J., & Dunbar, R. I. M. (2011). The brain opioid theory of social attachment: A review 
of the evidence. Behaviour, 148(9), 985–1025. http://doi.org/10.1163/000579511X596624 
MacLeod, C., Mathews, A., & Tata, P. (1986). Attentional bias in emotional disorders. Journal 
of Abnormal Psychology, 95(1), 15–20. http://doi.org/10.1037/0021-843X.95.1.15 
Maner, J. K., DeWall, C. N., Baumeister, R. F., & Schaller, M. (2007). Does social exclusion 
motivate interpersonal reconnection? Resolving the “porcupine problem.” Journal of 
Personality and Social Psychology, 92(1), 42–55. http://doi.org/10.1037/0022-3514.92.1.42 
Martel, F. L., Nevison, C. M., Simpson, M. J. A., & Keverne, E. B. (1995). Effects of opioid 
receptor blockade on the social behavior of rhesus monkeys living in large family groups. 
Developmental Psychobiology, 28(2), 71–84. http://doi.org/10.1002/dev.420280202 
Mogg, K., Bradley, B. P., De Bono, J., & Painter, M. (1997). Time course of attentional bias for 
threat information in non-clinical anxiety. Behaviour Research and Therapy, 35(4), 297–
303. http://doi.org/10.1016/S0005-7967(96)00109-X 
Panksepp, J. (1998). Affective neuroscience: The foundations of human and animal emotions. 
New York: Oxford University Press. 
Rosenberg, M. (1965). Society and the Adolescent Self-Image. Princeton, NJ: Princeton 
University Press. 
Tafarodi, R. W., & Milne, A. B. (2002). Decomposing global self-esteem. Journal of 
Personality, 70(4), 443–483. http://doi.org/10.1111/1467-6494.05017 
Watt, D. F., & Panksepp, J. (2009). Depression: An evolutionarily conserved mechanism to 

 
16
terminate separation distress? A review of aminergic, peptidergic, and neural network 
perspectives. Neuropsychoanalysis, 11(1), 7–51. 
http://doi.org/10.1080/15294145.2009.10773593