Save Multiply Checkboxes in a Widget

Trying to save multiply checkboxes in a widget, but no luck. Here is my code:

function update( $new_instance, $old_instance ) {
        $instance = $old_instance;
        $instance['title'] = strip_tags( $new_instance['title'] );
        $instance['social_displays'] =  $new_instance['social_displays'];

        return $instance;
}

function form( $instance ) {
//Defaults
$instance = wp_parse_args( (array) $instance, array( 'title' => '', 'social_displays' => '') );
$title = esc_attr( $instance['title'] );
$social_displays = array(
    'facebook_display' => array(
        'value' => 0,
        'label' => __( 'Facebook', 'higher' ),
    ),
'twitter_display' => array(
    'value' => 0,
    'label' => __( 'Twitter', 'higher' ),
),
);
?>
<p><label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:', 'higher'); ?></label> <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" /></p>

<label for="<?php echo $this->get_field_id('social_displays'); ?>"><?php _e('Which links would you like to display?', 'index'); ?></label><br />
<?php foreach ( $social_displays as $social_display ) { ?>
    <label class="description">
    <input name="<?php echo $this->get_field_name('social_displays'); ?>" type="checkbox" id="<?php echo $social_display; ?>" value="1" <?php checked(   $social_display['value'], 1 ); ?> />
    <?php echo $social_display['label']; ?>
    </label><br />
<?php
}
}

Any help, please?