face perception is modulation by sexual preference

Face Perception is Modulation by

Sexual Preference(Kranz & Ishai, 2006)

Melody Sinclair-Brooks PSYC 260

Introduction Hypothesis Methods Results Discussion My Opinion

Overview

Face perception is mediated by a distributed neural system in the human brain

Introduction

The response to faces is modulated by cognitive factors such as:

attention visual imagery emotion

Introduction

However, the effects of gender and sexual orientation on peoples response to faces is currently unknown.

Kranz & Ishai expected a significant relationship between the gender of the image presented and the sexual preference of the participant.

Greater response to an image will correspond to a greater activation in the reward circuitry regions of the brain

Sexual Preference Brain activation Response

Hypothesis

The reward circuitry consists of the dopaminergic pathways in the brain

These circuits are evolutionarily important for natural rewards such as food, music, and sex

The reward circuitry: The brain’s “pleasure center”

Heterosexual men and homosexual women are expected to respond more to female faces.

Heterosexual women and homosexual men are expected to respond more to male faces.

Researchers used fMRI to test whether subjects would respond more to their sexually preferred faces...

Methods

40 normal, right-handed subjects with normal vision (Mean age ± SD = 26 ± 3 years)

10 heterosexual women & 10 homosexual women

10 heterosexual men & 10 homosexual men

Subjects

Stimuli were projected onto a translucent screen placed at the feet of the subject

Subjects viewed: Grayscale photographs of faces (3 runs

each) and Assessed facial attractiveness (5 runs

each)

Procedure

Procedure Each run: Participants were shown images of faces

alternating with images of phase scrambled faces within a period of 30s

They had 21s for viewing and 12s for attractiveness rating

Each stimulus was presented for 3 seconds, with no blank periods between the stimuli

Face (3s) Phase-scrambled face (3s)

i. Viewing Condition: During the viewing condition, 60 male and 60

female unfamiliar, famous, and emotional faces were presented

ii. Attractiveness assessment: During the assessment of facial attractiveness,

100 male and 100 female faces were presented

Reaction times were recorded. The order of runs was randomized across subjects.

Procedure

ii. Attractiveness assessment (cont’d):

Subjects pressed 1 of 3 buttons to indicate whether a face was:

attractive neutral unattractive

Procedure

Independent Variables: Face or Phase-Scrambled face Sexual Preference

Dependent Variables: Attractiveness rating Brain activation

Whole body MR scanner (Philips Medical Systems, Best, The Netherlands)

Changes in the blood-oxygenation-level-dependent MRI signal were measured

High resolution structural images were collected in the same session for all the subjects

(180 axial slices)

The high-resolution anatomical images were used to build a 3D brain atlas

Data Acquisition

fMRI data analyzed in BrainVoyager QX Version 1.3

(Brain Innovation, Maastricht, The Netherlands)

All volumes were corrected for motion artifacts, realigned, and spatially smoothed with a 5mm FWHM Gaussian filter.

Data Analysis

inferior occipital gyrus (IOG) lateral fusiform gyrus (FG) superior temporal sulcus (STS) amygdala intraparietal sulcus (IPS) caudate putamen mediodorsal nucleus of the thalamus (mdT) anterior cingulate cortex (ACC) insula inferior frontal gyrus (IFG) medial orbitofrontal cortex (OFC)

Anatomical Regions Observed

The fMRI images for faces were subtracted from the fMRI images of the scrambled faces

This difference indicated the activation for

the brain areas when faces were being viewed

Scrambled Face signal – Face signal =Activation

Data Analysis

According to their attractiveness score

According to the mean of the parameter estimates that was calculated for attractive, neutral, and unattractive male and female faces

How were the trials sorted for each subject?

Between-subjects random-effects analyses to control for any random effects between subjects

What were the parameter estimates used for?

There was a significant interaction between stimulus gender and the sexual preference of the subject in the thalamus (mdT) and medial orbitofrontal cortex (OFC)

Heterosexual men and homosexual women responded more to female faces

Heterosexual women and homosexual men responded more to male faces

Results

mdT= mediodorsal nucleus of the thalamus

OFC = medial orbitofrontal cortex

Regardless of gender or sexual orientation, participants had very similar assessments of attractiveness of both male and female faces.

Results

Activation in the medial orbitofrontal cortex (OFC):

The OFC is involved in representing the reward value of sensory stimuli:

including beautiful faces, abstract positive and negative reinforcers

Activation in the thalamus (mdT) : it is reciprocally connected to the OFC and will

therefore show similar patterns of activation

Discussion

Facial beauty is considered an indicator of reproductive fitness – perhaps why men and women equally notice and respond to beauty of the same and opposite sex

Discussion

Recent studies have reported that facial beauty evokes activation in the reward circuitry regions of the brain...

Discussion

...... especially for reproductive success in sexually-relevant faces

I I WANT YOUR

BABIES.

Male and female face stimuli evoke similar neural activation within a distributed cortical network that includes: Visual, Limbic, and Prefrontal regions

Sexually relevant faces elicit stronger neural responses in the reward circuitry

Conclusion

Kranz & Ishai analyzed many brain regions, doing a thorough investigation

Perhaps they could have included diagrams for the procedure when explaining the steps as it was not crystal clear and provide an example of the phase-scrambled faces used

Future research could investigate the effect of peoples’ ethnic background on assessing attractiveness and activating certain brain areas

My Opinion

Questions?

Thank you.