Estou usando oRecyclerView como abaixo:

<android.support.v7.widget.RecyclerView
    android:id="@+id/list"
    android:layout_width="320dp"
    android:layout_height="match_parent"/>

e meu item da lista:

<LinearLayout  android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/selector_medium_high">
    <com.basf.suvinil.crie.ui.common.widget.CircleView
        android:id="@+id/circle"
        android:layout_width="22dp"
        android:layout_height="22dp"/>
    <TextView
        android:id="@+id/label"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minHeight="57.5dp"/>
</LinearLayout>

veja em detalhes esta parteandroid:background="@drawable/selector_medium_high" é um seletor normal:

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/background_high" android:state_activated="true"/>
    <item android:drawable="@color/background_high" android:state_pressed="true"/>
    <item android:drawable="@color/background_high" android:state_checked="true"/>
    <item android:drawable="@color/background_high" android:state_focused="true"/>
    <item android:drawable="@color/background_medium"/>
</selector>

mas quando executo esse código, não tenho alterações na cor de segundo plano quando toco na linha ....